Think Wire Quin is spot on here. Jamie brought huge amounts to the team in terms of guiding players around the pitch, boosting their self belief etc. If he does that again the club will win big here, even if his performances don't hit the heights we saw last time.
I don't think London could have made a better signing overall. Occasionally it's not just about the on pitch stuff. Bit like the time Rusty Bawden was brought back mid season as much due to his changing room presence as what he did on the pitch and helped turn a season around.