This is purely anecdotal--

For the three seasons previous to my last one, my all-world running back has won three league MVP's while averaging ~5 ypc. He is the backfield leader and had no chemistry problems with my journeyman QB.

My team, however, was the classic 9-7 good but not great squad. There were certain chemistry problems on the team overall.

Last draft, I traded up and grabbed a QB with a potential in the 80's. I started him last season. He did, however, have a conflict with my star RB.

There were no other chemistry problems with the team. Everyone else was neutral or an affinity.

Without any O-Line changes or loss in ratings for the RB, he went from ~5.0 a carry to ~4.0 a carry. He still had a good year--but not MVP good like he had been having.

My team, however, which had no business taking it to the next level talent wise made it all the way to the Front Office Bowl before bowing out to a far, far, better squad.

So--based on this small, anecdotal sample, I find that:

When my RB did not have a conflict with the QB, he was great. When he did have a conflict with the QB, he was good.

When my team had several conflicts, it was good. When it lost all conflicts (except for the RB), it became great.

What is other's experience.

Similar experiences here.

I've been all over the board on this. I've seen instances where removing one "cancer in the lockerroom" liberated the team and they finally one it all. In my current dynasty I had the opposite problem. Using the Browns into the 2006 Kevin Johnson of all people was the receivers leader and had extreme conflicts with two other receivers as well as a mild conflict with yet another.

His contract got too high to trade, he was just old enough I didn't want to resign him long term and I had a hot new rookie so I just cut him. My QB instantly went into a huge slump and started slinging INTs everywhere. My offense went from averaging over 27 per game to just a shade over 19. My running game was better than ever, but the passing game completely went into the crapper. The QB's rating (Marc Bulger) went from 2nd in the league at over 100 to finish in the low 80's. The only significant difference was cutting Kevin Johnson. And all those conflicts turned into affinities with the new leader, Chris Chambers. It was all the complete opposite of what I expected.

Now it's a new year and I traded Bulger and am elevating Eli Manning to start. I'm hoping for a clean slate in the passing game to change the course.