Holy bank account, Batman!
Now, to be fair, upgrading the offensive line was an obvious priority for Ryan Grigson and the Colts front office this offseason. When the franchise's owner is telling local media that the line was awful in 2012, that's a not-so-subtle suggestion to fix it. Cherlius is graded by places like Pro Football Focus graded him as the fifth-best offensive tackle available in free agency:
Summary: A player much maligned during his entire spell in Detroit, the inclusion of Cherilus this high up may surprise some people. In reality, his perceived performance level is not in line with his actual. Cherilus was in fact knocking on the door of All-Pro consideration at right tackle this season, and in the Lions’ extremely pass-heavy offense he played extremely well, recording a Pass Blocking Efficiency among the league’s Top 10 tackles (96.3).
The downside with Cherilus is that for a right tackle (if you still believe a right tackle needs to be your best run blocker) his run blocking is not overpowering and he has no experience on the quarterback’s blindside, having been held at right tackle by the Lions. Cherilus may not create any buzz with some very good tackles of a higher profile hitting the market, so some team may well get a bargain if they have to "settle" for Cherilus after the initial rush.
Rankings like this seemed to confuse local media in Detroit because the M.O. on Cherlius is that he's OK, but probably not worth the 17th overall pick in the 2008 NFL Draft. Cherlius was picked ahead of Joe Flacco, Chris Johnson, and Sam Baker just to name a few.
Personally, I wouldn't categorize a $10 million dollar signing bonus for Cherlius as a "bargain." It looks like Grigson overpaid for someone who might not be that much better than Winston Justice, who played well at RT last year for roughly $1.5 mill. I guess the difference between both is durability. Cherlius has started 71 of a possible 75 regular season games since he was drafted.