Jose Guillen has been placed on the 15-day disabled list with what Royals general manager Dayton Moore described as a Grade 2 tear of his right groin muscle. That sounds awfully bad, but Moore indicated that Guillen "wanted to play through it" and MLB.com reports that he's "expected to return after the 15 days."

The injury may put a temporary end to Mark Teahen's on-the-job training at second base, as the Royals moved Teahen into Guillen's old spot in right field for Friday afternoon's game and inserted Albert Callaspo at second base. That significantly improves Kansas City's defense and the offensive gap between Guillen and Callaspo likely isn't nearly as big as most people think.

Guillen drives in lots of runs because he hits in the middle of the lineup, has good power, and rarely passes up an RBI chance by drawing a walk, but his actual production isn't all that great. He batted .264/.300/.438 last season and .267/.318/.441 from 2006-2008. Not only is that about six percent worse than the average corner outfielder, it's close to what can be expected from Callaspo, who hit .306/.361/.371 in 74 games last season.

What will hurt the Royals more than losing Guillen is the fact that placing him on the DL opens up a roster spot for Sidney Ponson, who's set to take over as the team's fifth starter. For some reason Ponson seemingly gets an endless number of "second chances," but he hasn't had an ERA below 5.00 since way back in 2003 and this comeback won't go any better than similar stints with the Cardinals, Twins, Yankees, and Rangers.