Frank Lampard has been showing his age for the past few seasons. He's been injured on and off, seems to tire more easily and more frequently and has caught rather more criticism than one might expect of one of the Blues' best all-time players. He's also shown his class, adding a whole new position to his toolkit and becoming the club's leading scorer in the past 18 months.
Chelsea need Frank Lampard. They also can't lean on him quite as often as they'd like. So things are going to have to change a little bit:
[Lampard's] role doesn't have to change. What has to change is the way we analyse competition. Before we didn't analyse. Before it was: 'Every match, he plays.' Sometimes I wanted to give him a rest in a League Cup match and he would say: 'If you give me a rest, the next match I will not be the same because I have to play every three days.'
In this moment we have just to analyse competition and make some choices, because I believe he is the same player, with the difference that he is 35 and the time [needed] to recover from match to match is not the same for a man of 35 to a man of 25. That's the only point.
Note that this is what Chelsea have been trying to do with Lampard for years. The difference? Mourinho is being rather more reasonable about it than certain other managers. I suspect that Lampard himself will have quite a lot of say in which games he features in -- he's still an excellent player and in a more stable midfield should be able to compete against elite sides, and that alone will probably keep him happy.
Lampard knows he's getting up there, and he's almost certainly willing to pass the baton to the next generation. It's just a matter of showing respect for his accomplishments in the process. There's a difference between 'more rest and a reduced role'. Pretty easy, right?