I don't excuse Chavis for using PEDs because he and the people in his camp should know better. However, I can understand the willingness to forgive him and give him a second chance.
With Mejia getting caught 3 times, there's no excuse. I agree that MLB is setting a bad precedent by allowing Mejia back in.
When it was announced that the Sox signed Mejia, there was a fair amount of negative reaction from players around the league. None from our own players as far as I know, but I'm sure they weren't happy about it either. If Mejia makes the team, he is taking a roster spot from another player. Imagine the message being sent to that other player, who is presumably clean. MLB is basically telling those youngsters that it pays to cheat.