George Brett- 70's

Have Brett in two 70's Leagues and both seasons he's in his 77 card - .905 OPS.
STD stats:
Busch Stadium - .785 OPS
Oakland Stadium - .749 OPS

I did research another 70's League I was in and found his 77 card produced .916 OPS.

I might understand him underperforming in Oakland as everybody does, but Busch too?

Is it possible his 77 card rolls may be in error?

If you are expecting Brett to hit .905 OPS whenever you get his '77 card, you are going to be frequently disappointed. He will face better pitching than he did in real life, so it's expected on average that he will underperform. Sometimes he will overperform and reach or even exceed his .905 OPS, but most of the time he will not. (An exception might be if you have a super friendly hitter's park along with other hitter-friendly parks in your division.)

I have found, however, in the 60s game, my hitters perform closer to their real life numbers. I'm assuming because the talent pool of really good pitchers (and hitters for that matter) isn't as deep.

Despite the fact that the card says he has an "E" split in 77, he does not. Unlike some of his other years, you can/should play him against lefties, he still will have over a 100 OPS difference between righties and lefties. If he is facing a lot of lefty hitters, his OPS will be closer to 800. Maybe less than 800 in a pitcher park.

And RNG.