June missed 3 games last year. Probably injuries that he could have played through, if needed, but considering the Colts were killing it last year, no need to push it, so they coasted after that they took that first loss. Add to that the fact that June is in the position to make the big plays and is a 3 down LB, I'll take June.
Brackett played all 16 games. So, that's the big difference in your tackle numbers. Also, is Brackett a 3 down LB? I believe it was Thorton and June last year in the nickle. June and who this year?
As for June's skills, I think people are underestimating him. The guy is an athletic freak. As noted, a converted safety playing LB, but he has put on the necessary size to play the position and considering he plays a pursuit postion his skills fit perfectly.
My final observation, in watching the Colts last year, it just seemed like June was always around the ball. Hence, the big plays, but it's also good just to see a guy pursuing and being around the ball. It will continue to create opportunities for him.