First, the good news: You are not doing anything wrong and there should be no significant difference in these performances whether you sim games or play them out.
Now, the bad news which you are not going to want to hear: While I just took a look and verified that Delabar and Santos are having good seasons, thereby seeming to put the lie to your simulation results (the other two guys, not so good IRL):
- The way these guys were rated in the MLB game is based on brief careers of somewhat obscure players, and
- The game is going to vary performances in simulation compared to real life to some extent - this often disappoints simulators who expect OOTPB to mirror image actual results . . . and in advance (2013)!