I agree with this a bit. I've been on teams that had a ton of fun and didn't take it seriously and we won our division. Next session, they were intent on repeating and ended up in last place with the same players... Another team I was on was we started playing having fun and loose, at week 10 we were in first place and they got dreams of Vegas in their minds and started getting all serious. We ended up falling out of first, but luckily we won playoffs and eventually the City tournament and made it there, but it was pure luck towards the end that we made it.
Brian