In fairness I don't think we lost the Cl final due to tiredness necessarily, but it's true to say we weren't exactly leaping around like gazelles either. That said I think even the pro-rotationists wouldn't claim that it makes players run around more, or exude extra energy, I think the theory goes that it makes you kind of sharper, more alert, able to make better decisions etc etc.
I guess whether or not it works is best judged by how the team performed in the league, relative to how good the sum of the parts are. If you are of the opinion that us finishing 21 points behind the Champions is a true reflection on our merits, then it would be fair to say that the rotation had no effect last season. If you think we are actually a worse team than that, then you'd be thanking your lucky stars for the tinkering as it got us to the level we finished. If on the other hand you think that we are actually a better team than that, then you'd conclude that not only did the rotation not help us but it probably hindered us as well.
Rafa said that to be in a final you have to reach in a good moment, and he has a point, as he's reached several finals of different competitions.
The league is what tells how it works, but what do you look at, the position, or the points behind the first team? I think it's fair to admit, that at some points of last season Rafa didn't care much about the league, and it wasn't a rotation policy as such, but he was directly resting players to play them in Europe. Meaning, if the goal would have been to be closer in term of points to the first place, that could have been done by risking some players. Chelsea lost one of their defenders in the league that way and they probably paid for it against us in Europe. I don't know if people thinks that 14 points is better than 21 points behind Manchester, but at the end of the day it's a third place. If the 2nd place was close enough, it would have been worth to fight it, but at some moments of the last season we had no other goal than keeping the 3rd place.
But I do agree the league is a good indicator, I think this season the priority must be to win the league. And if this season we're not close enough to win the league, then it's fair enough to say the policy didn't work.
I agree when you say we could have made a more serious title challenge for the league. The squad was good enough to be much closer of the first team. But we didn't have a squad good enough to perform BOTH in the league, Champions and FA cup.
This year we do. When we play a "minor" cup, we're playing Leiva instead of Guthrie, Dudek and other guys we played against Arsenal yesteryear. We're stronger as a squad. It's time to attack the league now