Certain players have seemingly made my team worse, Bure being one of them. I really don't know what the magical factor is towards your team going brain-dead. My team right now is basically perfect, I feel no "tilt" and I've been winning at about a 90% pace ever since I made some changes, which included swapping out TOTW Hossa, TOTW Seabrook, and Karlsson for Kessel, Byfuglien, and McDonagh. Some people think team salary is a contributing factor, but I have a salary approaching $120 million right now so I doubt that's what does it. Probably some general team rating or something.
I don't chalk up getting shut out to tilt because goalies randomly have huge games in this game. But when my players can't pass, get outskated by mediocre players on the other team, and go offsides every chance they get despite having 100 chemistry, I can't help but think something to do with my team rating is weighing me down.
Last year, I thought it had to be salary-related. I played a lot more this year, with more high salary players and have debunked the salary theory, at least for myself. I started this year and played my first 50-75 games keeping my salary under 75 mil. For the past 200 games, my salary has been 90-105 mil and I play better. In both situations, what DID seem to tilt the scale of weirdness was the number of 90+ OVR players. If I kept them strictly in my top 6 (usually 4 of the 6) and first line defensive pairing, I would be fine, but if I tried using Pietrangelo on my second or third pairing OR having all 6 of my top 6 forwards above 90 then the players would start to feel off. Just no synergy, no one cutting to the net, bouncing the puck like a basketball in the neutral zone when a well-received pass would start a breakaway...and don't even think about adding a 90+ goalie to such a mess.
Not saying any of that is universal, because I think a lot of factors come in to play. This is what I've noticed in my 300+ games this year. After struggling to even get to Division 4 all year, I'm up to Division 2 after finding this lineup to be a keeper, even with the prices of these cards tanking:
Hossa - Datsyuk (C) - Backes (collection card)
Kane - Crosby - Kessel (collection)
Tarasenko (A) - TOTW Draisatl (86 OVR) - TOTW Bickell (collection)
Shaw - Kruger (+2 all) - F. Forsberg
Hedman (A) - Pietrangelo (collection)
Kronwall - TOTW 89 Carlson
McDonaugh - TOTW 89 E. Johnson
Bishop (meh)
Rinne (big meh)
I thought Crosby was awful on my first line. He did nothing for 15 games, but has been almost a PPG player on line 2. Same with Kessel. The guy just didn't do anything for dozens of games, but finally found a spot for him on line 2.