A world class triathlon athlete competes in a town where he was a torturer in his former life. Karma catches up, not only with him, but his whole team.

The second half of your logline reads more like a retrospective tagline. Try something that links in the main character and his goal better.
eg: When a world class triathlon athlete's career brings him back to the town he committed heinous crimes in he must fight to avoid the consequences of his mispent youth.

And why should his team suffer just because of his bad karma? Seems unfair.

And why should his team suffer just because of his bad karma? Seems unfair.