I know the actual criteria, just that June seems to be around the general time when super 2 starts to go out. If a guy has service time you would have to wait that extra time like say into July instead of June. Of course they have more of an impact than that. Say Gamel comes up to begin next year and has to be sent down after not hitting for a month. Well you just lost a year of service because you had him sit on the bench in September. You could easily(maybe not easily as the Liriano situation shows) leave him down a month plus to make his service time come up just short of a year. Crappy thing to do, yes, but overall the best way to keep the player cheap.