Most great teams don't use their bench much. I used to think that you need a big squad to compete, but it's really all about having a starting eleven where your 5-6 best players can start 50+ games each season. It's how we've won in the past too. The simple truth is that the invincibles would never have picked up a single trophy if Henry had missed half as many games as van Persie did for us. You look at Ibrahimovic who, up until his recent knee injury at the age of 35, had spent 40 days injured in total in his entire career. That's one of the big reasons he has won so much: all of his teams always had their best player available. That's the kind of consistency you need to win.
Our biggest failure in the last decade or so is to not fully realise this. We've invested incredible amounts of time in players whose only consistency was that they were bound to miss 2-3 months of each season. We've backed the wrong players and used the wrong approach towards teambuilding. At one point we had Cesc, van Persie, Nasri and Arshavin on our books in their prime, and I think they started less than 10 games together.