How is trying to answer the question of an apparent anomaly "bitching" ?

You should read the manual, under player usage and playing away games. It's pretty helpful regarding things like this.

From Away Games:

It is important to set these (MANAGER OPTIONS) unless you want the ROBOT to do it for you. If you have even one pitcher not set to a role, the ROBOT will set ALL your pitcher roles for you!

From Player Usage :

To determine who the GAME robot will select to start in this situation, use the following guidelines.

1. If there are one or more starters (pitchers with max-bats of at least 30) who have 30 BFA and are READY, the Game Robot will select the pitcher with the highest PB pitching grade.

2. If there is no READY starter the ROBOT will select a long reliever (with max bats less than 30) with at least 10 BFA.

* - NOTE : Quantrill is designated "SHORT RELIEF"

3. Failing the availability of pitchers designated in one and two above, the GAME ROBOT will select the highest PB rated reliever with either 10 BFA or full BFA.

Relievers who did not start: A reliever who did not start during the corresponding season can be used as a starter, but will be severely degraded by the GAME. This practice should only be tried in an emergency situation because in addition to the degradation of his skills, it is a severe drain on the reliever's innings.

The ROBOT will NEVER EVER choose an RP to start a game if there is an available SP, REGARDLESS of that pitchers PB ratings. If that were the case, then the computer would almost NEVER choose an SP, instead opting to start the Mariano Riveras of the world.
And the theory that Quantrill is chosen because he has "better numbers" is negated by the fact that he has not started in MLB this season, thus degrading his numbers in PB - as per the manual.

Obviously if a manager sets his options correctly, ther would have never been this discussion. However, on this occurance this particular manager did not. As a result, the ROBOT should, according to the manual, have made a certain choice, and it apparently didn't.

Unless there is more information that the manager has left out or simply not noticed (like setting Sele & Quantrill incorrectly), then this is a very valid thread.