He said: 'I think that whatever has happened, the situation with Shevchenko seems to be at the core of it.'
He also believes the speculation over Mourinho's future may unsettle
He said: 'I announced it at the start of the season and I just got a feeling as the season progressed a lot of them were saying 'ah well, he's not going to be here any longer...' and maybe some genuine concerns about 'who's going to take his place?' and just a relaxation possibly.
'But there was no doubt it had an effect and, once I decided not to retire, there was a genuine pick up again... it's amazing.'