Help me out here....

It's kind of hard to explain 100% because we don't really know the details of the deal Nigel was forced into, what happened afterwards, how the loan sharks had bet their money, etc. And to be honest, they probably didn't think it out too much. That whole gambling/loan shark subplot was very generic and sort of lazily written, right down to the stereotypical characters. Like a lot of the movie I guess. From what is said on screen, the loan sharks apparently have some sort of scheme that turns missed field goals into money, regardless of the outcome of the game. Whatever is going on, based on Nigel's reaction, we're left to assume that whether or not the loan sharks win their bet or he still owes them money, not being a participant in the deciding moments of the game lets him out of the part of the deal where he has to blow a kick or he loses his pub.

See you guys at the 10 year prison reunion - Ben Richards

Nigel had to botch the kick or lose his pub. He had a difficult choice to make because everyone knew he could make that 34 yard kick with his eyes closed. So the team would know he let them down. Falco took that away from him so Nigel did not have to throw the game. Therefore, Nigel kept his integrity.