Here's a look at the transactions this week that had the most significant fantasy impact.
Josh Donaldson, 3B - optioned to Triple-A Sacramento
Luke Hughes, IF - claimed off waivers from Minnesota
Impact: Donaldson was given an opportunity to get semi-regular at-bats while sharing the third-base duties in Oakland with Eric Sogard. He failed miserably, however, going 3-for-32 with no extra-base hits and 13 strikeouts. Hughes should get regular at-bats at third base with Oakland, though he's probably only worth a look in AL-only leagues until he can prove himself capable of handling major-league pitching. He came into 2012 with a career batting average of .224 in 294 at-bats.
Sergio Santos, RHP - placed on the 15-day DL (right shoulder)
Evan Crawford, LHP - recalled from Double-A New Hampshire
Impact: The Blue Jays will be without their closer for at least four weeks after Santos was placed on the DL with inflammation in his right shoulder. Fortunately for the Jays, they have an experienced closer in-house ready to step in and fill the void. Francisco Cordero came into this season with 327 career saves and will handle the ninth-inning duties for now. Although his velocity and strikeout numbers aren't where they used to be, he still managed to post a 2.45 ERA and a 1.02 WHIP while saving 37 games with the Reds last season. Crawford will work out of the pen in his first season in the major leagues.
Jair Jurrjens, RHP - optioned to Triple-A Gwinnett
Cory Gearrin, RHP - recalled from Triple-A Gwinnett
Impact: Jurrjens got off to a rocky start this year after a 2011 season in which he went 13-6 with a 2.96 ERA in 23 starts. In four starts this season, he was 0-2 with a 9.37 ERA and a horrible 2.45 WHIP. The Braves needed to free space in their rotation to make room for Tim Hudson, who is scheduled to come off the DL to face the Pirates on Sunday. Gearrin was awful last season with Atlanta, giving up 16 earned runs in 18.1 innings. He'll work out of the bullpen.
Ryan Dempster, RHP - placed on the 15-day DL (right quad)
Randy Wells, RHP - recalled from Triple-A Iowa
Impact: Dempster was off to a good start this season before the Cubs were forced to shut him down Saturday with a strained right quad. Through three starts, he had a 1.33 ERA with 23 strikeouts in 20.1 innings. Since moving from the bullpen to the rotation in 2008, he saw his ERA climb every year to 2011 when his ERA jumped to 4.80. His high strikeout rates in recent years still make him a useful part of a fantasy team, even when his ERA is less than stellar. His injury is not serious, so he should be back in action sometime in early May. Wells had his worst season last year, as his ERA rose to 4.99 and his strikeout rate wasn't nearly high enough to compensate. He likely has value only in deep leagues.
Daniel Hudson, RHP - placed on the 15-day DL (right shoulder)
Jonathan Albaladejo, RHP - recalled from Triple-A Reno
Impact: Hudson has been diagnosed with an impingement in his right shoulder, and manager Kirk Gibson is optimistic he won't miss too much time. Unfortunately, that is the same diagnosis that was given to former D-Back Brandon Webb in 2009, so it's hard to say for sure how long he'll be out. In his first full season as a starter last year, Hudson went 16-12 with a 3.49 ERA and 169 strikeouts in 222 innings. Long reliever Wade Miley was called upon to fill Hudson's spot in the rotation and is not likely to have much fantasy value based on his minor-league track record and hitter-friendly home ballpark.
Aubrey Huff, OF-1B - placed on the 15-day DL (anxiety)
Joaquin Arias, IF - contract purchased from Triple-A Fresno
Impact: Huff will miss some time as he receives treatment after suffering an anxiety attack. He had a disappointing 2011, as he hit just .246 with 12 home runs and 59 RBI in 150 games, and he started poorly this season as well. His DL stint means that Brandon Belt and Brett Pill should receive extra at-bats at first base. Belt started the year as the regular first baseman but ended up losing playing time to Nate Schierholtz after going 1-for-10 with five strikeouts through his first three games. He has since turned things around, going 6-for-19 (.316) over his next 10 games, bringing his season average up to .241. Pill has gone 6-for-17 (.353) with a home run and three RBI. Arias gives the Giants some middle infield depth.
Jason Bay, OF - placed on the 15-day DL (ribs)
Zach Lutz, IF - recalled from Triple-A Buffalo
Impact: Once an elite fantasy baseball star, Bay put together back-to-back disappointing seasons with the Mets in 2010 and 2011. Over those two years he managed to hit just .251 with a slugging percentage of only .386 while missing significant time due to injuries. He hoped to take advantage of Citi Field's more hitter-friendly dimensions this season, but will now be shut down due to a nondisplaced fracture of a rib in his left side. He suffered the injury while attempting a catch Monday and it is unclear how long he'll be out. Mike Baxter, Scott Hairston and rookie Jordany Valdespin could see time in left field while Bay is out. Andres Torres' impending return and the hot play of rookie Kirk Nieuwenhuis also muddy the outfield situation. For fantasy purposes, it's probably best to avoid this mess altogether until it sorts itself out. Lutz is unlikely to receive enough playing time to make him fantasy relevant.
Mike Pelfrey, RHP - placed on the 15-day DL (right elbow)
Robert Carson, LHP - recalled from Double-A Binghampton
Impact: Pelfrey has been a decent starter the last four years, as he started at least 31 games in each of those seasons while going a combined 45-45 with a 4.27 ERA. Unfortunately for potential fantasy owners, his low strikeout rates have made him a risky pick in leagues with innings limits. He should miss significant time, possibly even undergoing season-ending surgery after an MRI showed a partial UCL tear in his right elbow. Chris Schwinden is expected to get promoted in time to fill Pelfrey's spot in the rotation Friday. He's a risky fantasy option at this point, as his minor-league numbers have shown him to be quite hittable. Carson gave the Mets an extra left-handed arm out of the pen and was then sent down to make room on the roster for the eventual callup of Schwinden.
Cliff Lee, LHP - placed on the 15-day DL (left oblique)
Joe Savery, LHP - recalled from Triple-A Lehigh Valley
Impact: The Phillies lost one of their aces after he strained his left oblique during a 10-inning gem against the Giants last Wednesday (a game which the Phillies eventually lost). The team made it official Saturday, placing him on the DL. He's hopeful that he'll be able to return to action when he becomes eligible May 4. Kyle Kendrick moved from the bullpen to the rotation to fill the vacant spot and was lit up for seven earned runs in three innings against Arizona on Monday. His strikeout rates have been quite low throughout his major league career and his ERA has fluctuated quite a bit from year to year, making him a risky fantasy pick. Savery will work out of the bullpen.
Marlon Byrd, OF - acquired from Chicago Cubs for RHP Michael Bowden and a player to be named
Nate Spears, IF - designated for assignment
Impact: With both Carl Crawford and Jacoby Ellsbury on the shelf with injuries, the Red Sox added some outfield depth by acquiring the veteran Byrd from the Cubs. Byrd has posted a batting average of at least .276 for five seasons in a row, though his counting stats have not been of much value in most fantasy leagues. He struggled mightily in his 13 games with the Cubs this year, hitting just .070 (3-for-43) with no extra base hits. In eight at-bats with Boston between 2011 and 2012, Spears was hitless with four strikeouts. He has since accepted an assignment to Triple-A Pawtucket.