Below are some brief round-ups and details of the recent developments, as well as some analysis of what the injuries could do to fantasy rosters.

Evan Longoria - 3B, Tampa Bay Rays
The Tampa Bay Rays, along with fantasy owners, were dealt a huge blow this week when slugging third baseman Evan Longoria was placed on the 15 day disabled list with a partial tear of his left hamstring.  Longoria suffered the injury during an awkward slide into second base in the Rays' win over Seattle on Monday night, though the extent of it wasn't initially known.  Further reports have Longoria missing six to eight weeks of the season, which will hugely impact the Rays batting order and fantasy rosters.  In 2012, the 26 year-old was hitting .329 with 4 home runs and 19 RBI and was well on his way to another season as one of the American League's most productive young hitters.  The Rays will rotate players throughout their lineup to compensate for Longoria's absence, and it's possible that Elliot Johnson, Sean Rodriguez, and Jeff Keppinger will all see time at the hot corner until his return.  Fantasy owners might not have much of a play here, since Johnson hasn't proven much as a hitter and Rodriguez and Keppinger were already seeing regular time in the Tampa infield.

Josh Hamilton - OF, Texas Rangers
Rangers outfielder Josh Hamilton is no stranger to minor injuries, and he suffered yet another on Sunday when he exited Texas' game against the Rays with back spasms.  He's listed as day-to-day and was not in the lineup for the Rangers on Monday or Tuesday, but early indications are that the problem is not serious and he was held out with back stiffness more as a precaution than anything else.  Texas has opened the year very strongly and has great hitting depth (particularly in the outfield), so it's not surprising that they would give Josh some rest before allowing him to get back in the lineup.  Should Hamilton miss any additional time, outfielders David Murphy and Craig Gentry could both see increased at-bats at the centerfielder spot, instead of their usual platoon in left field.  Youngster Brandon Snyder could also see time in the Texas outfield, though he hasn't done much to warrant fantasy consideration yet.

Nick Swisher - OF/1B, New York Yankees
A very productive month of April came to a difficult end for Yankees rightfielder Nick Swisher on Sunday when he pulled his left hamstring.  He will miss several games and may not return until next week, though the team is apparently not going to place him on the disabled list.  Swisher was hitting .284 with 6 home runs and 23 RBI at the time of his injury.  With Andruw Jones already filling in for Brett Gardner until his return from the disabled list, it's likely that the Yankees will use utility man Eduardo Nunez in left field and Jones in right until either Gardner or Swisher is ready to re-enter the lineup.  Nunez has not played the outfield much in his major league career but appears capable of handling his new role.  The 24 year-old stole 22 bases for the Yankees last year and will make most of his fantasy impact on the basepaths, though his eligibility at three infield spots (and now the outfield) make him worth consideration in many leagues.  As for Swisher, he could be back for the series versus the Rays on Tuesday.

Justin Morneau - 1B/DH, Minnesota Twins
While Twins first baseman and designated hitter Justin Morneau wasn't off to a great start in 2012, with just a .230 batting average, 4 home runs, and 9 RBI thus far, he had been largely healthy and was set to have a comeback season.  That plan, however, was derailed when he left Monday's game against the Angels with soreness in his left wrist.  That same wrist underwent surgery in September of last year to repair some tendon damage, so things certainly didn't look favorable for the 30 year-old.  Fortunately, an MRI back in Minnesota on Tuesday revealed that his wrist had no structural damage and Justin is set to rejoin his club for their series in Seattle staring on Friday.  It's possible that, for the sake of caution, he may not return immediately, but the MRI results are certainly a welcome bit of news for a player who has dealt with concussion symptoms and this wrist ailment in the last few years.  If he is out of the lineup, it's likely that the Twins would use Joe Mauer as their designated hitter and either Ryan Doumit or recently recalled Drew Butera as their catcher, with Chris Parmelee still getting his usual starts at first base.  Fantasy owners who invested in Morneau's comeback prospects are likely disappointed but, if he returns quickly and with no ill effects, he could resume his quest for a solid performance in a nearly full 2012 campaign.

Kevin Youkilis - 1B/3B, Boston Red Sox
With 2011 AL MVP runner-up Jacoby Ellsbury already on the disabled list, the Red Sox suffered another injury over the weekend when starting third baseman Kevin Youkilis was scratched from the lineup with tightness in his lower back.  Youkilis has not played since then and his spot at the hot corner has been filled by veteran utility man Nick Punto, who is a capable fielder but provides very little offensive help aside from a few stolen bases.  It's unclear at this point if the Red Sox will need to place the 33 year-old Youkilis on the disabled list, but as a precaution (and to bolster their infield) they recalled 22 year-old shortstop prospect Jose Iglesias.  The Cuban-born Iglesias could fill in at shortstop during Youkilis' absence, with starter Mike Aviles moving to play third base.  Punto will also see more playing time, and he got the start on Tuesday.  Youk was off to a slow start in 2012 and was hitting just .219 with 2 home runs and 9 RBI thus far, though he had raised his season average from .174 since April 23rd.  If he misses any significant amount of time, the Red Sox could also recall 23 year-old third baseman Will Middlebrooks, who is off to a red-hot start for Triple-A Pawtucket this year.  Baseball America ranked Middlebrooks as the club's top prospect entering 2012 and projects him as a future star.  Of any Youkilis replacement, he would have the most fantasy impact, since Iglesias has shown little with the bat in the last two years and Punto's contributions are minimal.