I like this move, I really do. If Mark Teahen can play even average defense then KC may have just made their team better without dipping into free agency. I know I have been all about Alberto Callaspo starting but that was in favor of Grudz or another free agent lacking his on-base skill. Teahen put up OBPs of .357 & .353 in '06 & '07 and though it dipped to a Jacobs-like .313 last season I think he will rebound.
Even if Callaspo gets the starting nod it just adds another position for Teahen to sub making it likely that he could start four or five times a week each at a different spot. But back to the possibility of Teahen starting at 2nd, we could potentially see a lineup like this:
Crisp - CF
Aviles - SS
DDJ - LF
Guillen - RF
Jacobs - DH
Gordon - 3B
Butler - 1B
Teahen - 2B
Olivo - C
According to the Lineup Analysis at Baseball Musing (using career rate stats) this lineup would average 4.85 runs a game. (In 2008 KC averaged 4.26 runs per game.) I think if they could pull that off they could be looking at an 85 win season. I think Gordon, Butler, & Teahen will all be better than they were last season and you could make the argument (and be right) that Guillen & Jacobs couldn't possibly be worse which could push them to around 5.0 a game.
Replacing Teahen with Callaspo dropped it to 4.72 rpg, which is basically 21 runs over the course of a full season. Now if Callaspo was an above average defender you could wave that off but he's not so if Teahen at 2nd makes KC better offensively then they should pursue it. (Some may give Trey kudos for thinking outside the box but I'm not because it was outside the box thinking that gave a guy with a .348 SLG pct most of the starts at 1st base last year.)
Much like the Teahen CF experiment of '07 it's worth a shot.