Call me crazy, but I think the solution to frontlines is simple. Make 2nd place wins add to the achievement score in some meaningful way, how about .5 an achievement point? May take some minor coding. Sure it will change the dynamic a bit... but currently there is just way too much to acquire in frontlines and the grind is absolutely pure RNG and sucks miserably.
I'm not going to even rant about the poor balance and how healers are shafted with the frontline bonus ranking.