In response to mef429's comment:
i understand what your saying now. its certainly a tempting scenario. i know he probably won't save 100 more hits than the average SS but i get your math. I'm also eager to see that glove in action and how it affects our pitching staff (granted it won't help with the long ball) but our up the middle defense will be the best in the league with iggy, pedey and big number 2 all getting GGs. even middlebrooks surprised me with his defense last season. i wasn't expecting much from him but he made some real good plays.
Ciriaco is a very good defensive SS, perhaps even excellent and close to Iggy's level, so an Iggy gain on defense is not going to be 100 plays saved over 150 games. I want to say that I used this same argument about Iggy last winter, but wrongly assumed that Aviles was a below average SS, particularly in the range factor area. As it turned out, Aviles did better than average and wiped out the plays made differential to a pretty large extent. (His offense was below what I had projected after a nice start.)
I do want to point out that 100 plays saved over 150 games is not fantasy. Perhaps it is more like 50-75 over an average SS and 75-150 over the bottom fielders, but the numbers over the past few seasons show some pretty massive disparities between the best and the worst SSs by plays made per 9 innings.
I provided the numbers last year, and I found that a few top ranged SSs made 100-150 more plays in about the same innings as other ML SSs.
Here's alook at 2012:
SSs with 1350+ innings & plays made (PO+A)
A Ram 1392/661
*** Hardy made over 150 more plays per 150 games than Rollins and about 120 more than Reyes.
SSs with 1150-1350 innings:
*** Y Escobar made 150 more plays than Jeter in less than 150 games.
The numbers are real. The theory is sound. A great fielding SS can shave a lot off a teams ERA and help us win as much or more than a good hitting poor fielding SS.