In David DeJesus, the A's acquire an above-average player toward the end of his peak, under control for one year at the very reasonable price of $6 million. DeJesus can play center, but is best suited to left field where his range is above-average and his fringy (at best) arm is less of an issue.
He's a smart, disciplined hitter whose walk totals have never been great -- although the Royals have not encouraged that kind of patience for most of DeJesus' career -- but who makes good decisions at the plate and boasts a very high contact rate. He rarely gets beaten within the zone or chases bad balls outside of it. He's not futile against southpaws, with just a modest platoon split, so he can play every day, or close to it, as his health allows. He did miss the second half of 2010 due to a torn ligament in his right thumb, and hand injuries can linger for a year or more after they're superficially healed, often sapping power in the process.
In exchange for a year of DeJesus's services, the Royals acquire right-hander Vin Mazzaro and left-hander Justin Marks. I've never been a big Mazzaro fan, and I am even less of one now that his velocity has taken a step backwards. He was up to 94 or better in 2009 but was most 90-92 this past season. His best secondary pitch is a slider that breaks down without much tilt. He also throws a slow-breaking curve and a well below-average changeup.
His best shot, short of developing a new pitch, is to improve his control, as right now he's a replacement-level starter attractive for his low salary rather than his potential.
Marks is a solid inventory prospect but doesn't compare well to the plethora of left-handed pitching prospects in Kansas City's system. He'll show a solid-average fastball and a fringy slider, but his changeup remains fringy and right-handed hitters hit him well in 2010. He shut down lefties well enough that he could probably have a solid career as a left-handed specialist if nothing else improves. He was old for Kane County this year and didn't pitch especially well.
All in all this looks like a sound cost-saving move for Kansas City where they add some pitching depth at low salaries, but where neither pitcher coming back projects as a medium-impact player.