This.
I would like to think that players are professional enough to give it their all at a loan club, but sadly in some cases it just doesn't happen, does it Muntari?
Logically they probably give it their all. However, when it's crunch time, do they have the loyalty and passion for the club to dig deep and pull out the motivation to succeed? I doubt it.
It doesn't make much sense really. I mean if it isn't their club, and their loan is finite, why would they care THAT much? It's just that little edge which is missing.
It also depends on the reception they're receiving. Ben Arfa flourished in the few games he played because the toon army metaphorically sucked his length every second he was on the pitch. Incredible reception and that goal against Everton put him in our good books big style.
Now if you have a number of loan players, and the going gets tough, and negativity sets in from fans and the media, I think they would have far less patience and tolerance to accept it. After all, the clubs fans aren't their fans. They have their own club and fans elsewhere.
You need a solid permanent team which is signed to the club. Sure, bring in someone good on loan. He'll be unique and he'll feel special (like Ben Arfa did). However, if you bring in 4 or 5 on-loan players, it just changes the whole dynamic of the team.