Danny Valencia exploded onto the scene for the Minnesota Twins in the middle of 2010. In half a season of work, he notched a .351 wOBA, hitting seven home runs in the process. His performance was good enough for third place in the Rookie of the Year voting. It was supported by an unsustainable .345 BABIP, but the Twins didn't have any other options; besides, why argue with results?
They gave him a full season to prove his worth in 2011, but he flunked the test. He played 154 games with a wOBA of .297, easily the lowest among qualified AL third basemen that year. A large part of the reason was that fewer balls fell in for hits; his BABIP for the full season was a more normal-looking (but still low) .275.
Why the low BABIP? It's likely that pitchers and defenses adjusted to him, but he couldn't adjust back enough to hit the ball with authority. He struck out too often (nearly 17% of the time) and didn't walk enough (6.2%). When he did hit the ball, he couldn't hit it hard enough (17.8% LD rate, 8.9% HR/FB rate) to compensate for his lack of contact.
Still, over the course of a full season it became clear that Valencia had one distinct strength: he could crush left-handed pitching (.358 wOBA vs. lefties against a .276 wOBA vs. righties). He also struck out less frequently, and walked more frequently, against lefties than he did against righties.
Valencia started the 2012 season at third base again; however, he cratered almost immediately. He just wasn't seeing the ball well. His strikeout rate shot up to 22.3% at the same time his walk rate plummeted to 1.9%. He hit half of his balls on the ground, and when they were in the air, they rarely left the yard (3.6% HR/FB rate). Barely 14% of his hits went for line drives. It's no wonder he finished the first half with an execrable .213 wOBA.
There's no record of an injury or anything else that would explain the fall. It's possible he was playing through something, but we can only speculate at that. Whatever the case, he played himself out of a full-time position when the Twins called up Trevor Plouffe to man the hot corner.
When Plouffe started doing well, Valencia was shipped to the Red Sox for a fringe minor-leaguer. The Red Sox placed him in AAA but called him up to the bigs when Will Middlebrooks fractured his right wrist. Middlebrooks had been outstanding up to that point, so Valencia obviously wasn't intended to be a full-time player in Boston. When the season ended, the Red Sox DFA'd him. Dan Duquette picked him up just eight days later for cash considerations.
Since the Orioles have a full-time third baseman and the other easier spots on the defensive spectrum are covered, the Orioles have used Valencia primarily as a DH against left-handed starters. He's not only rewarded the Orioles with a .458 wOBA vs. lefties, but also found a way to be only slightly-below-average against righties (.317 wOBA). Sure, he's struck out in 25% of his PAs against righties and gotten only three hits -- but those hits have all left the yard! In addition, he's tacked on an 8.3% walk rate. This output is much appreciated because, as Eat More Esskay noted, the Orioles' DH spot is currently third-to-last in the AL by OPS. Without Valencia's bat, it would be much worse.
Since Danny can't be an everyday DH, the team needs a consistent righty masher to platoon with him. Luckily, such a person exists in the form of Wilson Betemit (career .370 wOBA vs. righties). Betemit is on his way back from an injury, but once he rejoins the team, the low offense at DH should improve dramatically.
Get will soon, Wilson!