Squad Rotation Considered Harmful

Bill Shankly famously used to quip, when asked what his side was for a forthcoming game: "It's the same as last season." Indeed, when Liverpool won the league in 1965/66—Shankly's second title—he used only 14 players. Even more remarkably, one of them played in only 1 game, while another made only 5 appearances.
Of course, back then, teams could name only a single substitute, who might or might not be used. (In fact, prior to the 1965/66 season, no substitutes were allowed!) Also, the top division contained 22 teams, instead of today's 20, so that a full league season was 42 games, not 38. That season, Liverpool also competed in the FA Cup, the UEFA Cup Winner's Cup and the FA Charity Shield (they were FA Cup winners for the first time in the 1964/65 season). That season, they also reached the final of the now defunct Cup Winner's Cup where they lost in the final to Borussia Dortmund. (They did not participate in the Football League Cup that year.) I mention this because the pro-squad rotation brigade love to point out how many fixtures teams play each year, and how tired players get. What a load of, er, poppycock!
Fact: Shankly's 1965/66 championship-winning team played 53 games that season, compared to Rodger's 2014/15 7th placed side playing 58. Not a huge difference, particularly when you bear in mind that Rodgers is able to play 3 substitutes each game, while Shanks was limited to just the one.
It must be accepted that injuries and disciplinary suspensions play a big part in team selection. Shankly was lucky that injuries didn't play too big a role in his season, but he probably made sure that his players' discipline—historically, always a Liverpool strong-point—wasn't too big a factor. But why didn't he use more players anyway? It wasn't as if Liverpool had a small squad. The simple answer is that, back then, the Liverpool management's philosophy, as it was just about everywhere else at the time, was summed-up by the old adage that you never change a winning team.
Like many football clichés, there's an amazing amount of wisdom contained in those few words.

The Systems Approach

The modern fashion, which has become so accepted that many people—unfortunately, many of them managers—have come to see it as fact, is for players to be viewed as interchangeable components in a system.

That is, the manager formulates one or more attacking and defensive systems for a particular game, and drills players on each position within that system, together with their roles and responsibilities. His tactics for the game will be based around such systems. He'll pick a starting 11 on the basis of what he regards as the best overall allocation of players available in his squad to each role. (It's fair to say that he might also select systems that favor the better of his available players, but, then again, he might not.) If a player gets injured, or isn't playing his position too well, he'll pick a sub who can slot into the same position so that the team's tactical plan doesn't get too disrupted. If the system isn't working, he'll switch to a different, preplanned alternative, reassigning players to new positions within the new system and possibly making tactical substitutions—selecting players from the bench who might play particular roles better than his starters. Clearly, in such an environment, managers favor versatile players who can slot into a variety of positions, and thus provide the manager with more options. By contrast, specialists, such as an out-and-out center-forward, who can score headers from outside the box and who can be stopped in his tracks only by deployment of a tactical nuclear warhead, are viewed as dinosaurs that have no place in the modern game.

The advantage of systems, from the managers perspective, is that it simplifies his approach to the game. He can plan in such terms without necessarily worrying about which players he intends to use. If a player is injured during prematch training, or picks up a suspension, he can pick another player to do the same job and nothing else changes. He can also sound modern, knowledgeable and scientific when talking the language of systems to his Board of Directors when asking for funds to recruit players whose skills fill the gaps in the current squad's capabilities.

When managers implement squad rotation, they're not so much resting players for a game and picking replacements—although that definitely happens for less important matches, such as early rounds of the Football League Cup—as they're picking players that fit the systems they intend to deploy, which naturally causes the team to change from game to game.

The Human Element

Unfortunately, the systems approach above is all a load of hogwash.
Players aren't merely components, they are people with a complex mix of emotions, motivations and self-confidence as well as more measurable, traditional attributes such as passing, tackling, heading, sprinting, etc. abilities.

Consider a game in which a player—let's call him Alf—is selected, for the first time in, say, 10 games, to play a man-marking midfield role aimed at neutralizing an opposition playmaker. Grasping his opportunity, he plays a blinder, not just doing his job, but chipping in with a couple of assists and scoring a 30-yard screamer just before the final whistle. He's now on a high, knowing that he helped secure the win and confident that the boss will have no option but to pick him for the next game. Why is this? Because players are ultimately motivated to be in the starting XI, and expect to play in the next game if they've played well. After all, that's only fair.

But systems aren't fair. In his team's next match, there is no star playmaker in the opposition's midfield. Instead, they have a couple of more agricultural central midfielders who ply their trade with a tad more emphasis on brute force than on skill. As a result, Alf's manager isn't even thinking of him for the next game. If he's lucky, he might be given a token slot on the bench, without actually figuring in the manager's plans.

Now put yourself in Alf's boots. He did what was asked of him, and now he's an unused sub. Next game, he might not even make the bench, as it's amazing how quickly a good performance will be forgotten by the media and fans, never mind the manager. How would you feel about that? Dispirited? Annoyed? Frustrated? However you feel, you're not exactly going to be exuding team spirit for the next few games, are you? Not unless you've suffered severe head trauma going for a 50-50 header more often than is advisable, anyway.

By the time Alf's next outing comes around, the lack of game-time has affected his match fitness (I would contend that no amount of training can replicate the big game atmosphere, screaming fans, TV crews and adrenaline rush of a Premier League game on a Saturday afternoon). He's less sure that he'll receive his just desserts if he plays his heart out, so he makes sure he plays within himself and doesn't get injured. As a result, his timing is a little off, some of his passes go astray, and before you know it, his number's up on a board and he's heading back to the bench. It didn't help that his team-mates had little game-time experience playing with him, or he with them, so they didn't get a chance to gel—that magical quality in which players seem to read each others minds, and just know what each other are going to do. But that doesn't matter to the boss, because players gelling is just too intangible a benefit. Worse yet, it involves players thinking for themselves and doing things that are beyond his control.

Giving the Opposition a Boost

One of my pet frustrations with the systems/squad rotation approach is exemplified by the tweaking that Rafa Benítez used to perform on a regular basis. Faced with Manchester United on a Saturday, he'd play all of his star players and put out his best team. There would only be three points on offer, but Benítez was never one to shy away from the big occasion. Then, the following Wednesday, we'd play a team from the relegation zone, let's call them Sad FC, and Rafa would immediately give Xabi Alonso a day off,  tell Fernando Torres to head to home to the beach, etc. The result was that he'd put out maybe five or six of the players who featured in the weekend fixture to try to win the same number of points against the more lowly side just 4 days later.

Needless to say, his record wasn't exactly brilliant on such occasions. (I need to analyze the stats, but I wouldn't be at all surprised if we didn't get more points from the big games than from the allegedly easy games.)

Why?

Well, imagine you're the manager of Sad FC. You watched Liverpool play top-draw football against United on Match of the Day, you've reviewed all the scouting reports and now you're worried that Liverpool are going to explode all over you on Wednesday evening. But wait! Benítez has just announced his team and it's practically their reserve side. You go in to see your players in the dressing room and tell them: "I'm angry. Benítez is being disrespectful to you guys. Instead of putting out his best team, he's sending out their youth team to play us, and he thinks he's going to win. I'd have been worried if Alonso and Torres were in the side, but they're not. You're way better than these kids. Let's show them that they can't expect to simply show up and beat us. In fact, let's give them a bloody nose for their conceit!".

In other words, not only was Benítez leveling the playing field by resting his better players, he was also giving his opponents a psychological boost, because they knew they were being handed an opportunity to win.

Never Change a Winning Team

This is, to me, just about the best piece of advice any manager in football can get.

In no particular order, here's why I think this:

• Players want to play in the first team and win games. They know that if they win, avoid bookings and stay fit, they'll play in the next game. In other words, their motivations and expectations are now in alignment with that of the club.
• First XI players are far less likely to get a booking, because they know it might cost them a place in the side.
• Players in the first XI never become complacent, because they can see the hunger of the reserve team players who are itching to take their place. They know that they can only hold them off by winning each game.
• Players who make the bench can have no complaints if the team is winning. This makes it easier to come to terms with why they're not in the side, while helping them to focus on being ready to take their place in the side when the team fails to win. Having experienced time on the bench, they will not want to return to it and will be motivated to keep on winning when they make the side. That way, they could keep a star player out of the lineup as long as the team keeps winning.
• The starting XI, once they start to rack up the wins, increase in confidence. But they don't become too confident because they know they're just one draw away from being dropped. Confident sides win more than teams that doubt their abilities. (As proof of this, ask yourself why it is that the home side has a statistical advantage over the away side. If systems and tactics are all there is to it, why does every team typically have a better home record than they do an away record? Because the home team gets a confidence boost from the home fans' support.)
• The more players play together, the more they gel as a team. They become more consistent and interact with each other with far greater understanding.
• Managers who must deal with the same team that won their previous game must now focus on the strengths of that team relative to the opposition, and worry less about the strengths of the opposition. This develops a "they've got to deal with us" mentality rather than a "how do we nullify them" approach. The former exudes confidence, the latter insecurity.
• Instead of thinking about systems and the components within those systems, managers must now consider what their players offer. This allows specialist players, as well as the generalists, to shine. Once the manager understands that players can provide more than a system position requires, they can harness those additional abilities and optimize their application.
• Opposition teams lose confidence when they see that you really are going to put out the same team that demolished your previous opponents 5-0. Instead of planning how to win, they start planning how not to lose by big margins. Rest players, and they'll only gain in confidence.
• Fitness is almost never an issue for professional athletes. If they're not 100% fit, then you must drop them from the side. But not before that. Resting a player who is currently 100% fit because you're worried he'll only be 80% fit for the following game is a self-fulfilling prophecy. Put him in the side, win the game (or try to) and drop him if it turns out he actually isn't fit for the next game. (As I mentioned in my previous post about the Stoke vs. Liverpool game, look at how Jose Mourinho managed John Terry, compared to how Brendan Rodgers managed Steven Gerrard. There's simply no comparison.)
• First team players who play well know that they'll be rewarded with another game, so they don't become dispirited by getting dropped after playing well and winning. Similarly, players who play poorly and lose can have no complaints if they're subsequently dropped.
• It may come as a surprise to learn that many managers do not know their best team. They may think that player A is better than player B, but they're often wrong. One interesting aspect of Never Change a Winning Team is that, almost by a process of natural selection, the best players—or maybe it might be more accurate to say the best team—naturally gravitate to the starting XI.

I rest my case.