I'll say it can be influenced with referees. There were a myriad of questionable calls in SB 50 and even more no calls. While it's not proof of anything, I find Talib's tossing of Philly Brown by the facemask and the subsequent 25k fine disgusting. Talib came out after the game and said he deliberately tried to hurt PB and take him out of the game. And the NFL laughed and said good job. Even Broncos fans I was with when it happened said he should have been ejected. There were calls that were so blatantly wrong it absolutely influenced the outcome, and by the NFLs reaction, it would give one reason to think they approved.