I used bWAR. Just looking at the NL, annual WAR leaders for 25 of the past 50 years played on first-place teams (plus one Wild Card that made the World Series). Every guy is either a Hall of Famer or good enough for future consideration: Bench, Stargell, Morgan, Schmidt, Bonds, Bagwell, Pujols, Posey, Bryant, Yelich, Bellinger, and 2020 leader Betts (I would say maybe not Bryant, but Boston did show a video of him to Mookie to infer he's not Kris... and they were right; ugh).
As pointed out, I'm sure it's not the same for the AL because of Trout.