Tonight's match-up between the Pittsburgh Pirates and Cincinnati Reds marks the major league debut of baseball's top minor league hitting prospect, CF Jay Bruce.  He has presumably taken over the CF position from the ineffective Corey Patterson.  There will be little to no second-guessing of this move.

How could anyone argue against replacing a player with a slashstat line of 201/242/354?  I can't do so on hitting grounds.  No matter how few walks Bruce was taking in AAA (12 in 184 ABs) or how frequently he struck out (45), he would have to be a complete disaster not to top Patterson's efforts.

Where Bruce may have more of an effect will be defensively.  While Patterson was one of the worst hitting CFers, he ranked very high in two of the more popular defensive statisitics, Range Factor and Zone Rating.

Range Factor (RF): ((PO + A) divided by innings)

Zone Rating (ZR): The percentage of balls fielded by a player in his typical defensive "zone," as measured by STATS, Inc.

Patterson was first amongst the 13 qualifying NL CFers in ZR and 4th in RF.  Can we expect Jay Bruce to do the same?  If we can not, won't that have a negative effect on the pitchers of Cincinnati?