Here's a look at the transactions this week that had the most significant fantasy impact.
Jed Lowrie, SS - activated from the 15-day DL
Impact: Lowrie was fairly productive with the bat before missing a couple months with a sprained right ankle. The shortstop was hitting .253 with 14 home runs and 36 RBI in 80 games before he injured the ankle July 14. He should be a regular in the Astros lineup for rest of the season and could be an asset in many fantasy leagues. Tyler Greene handled the shortstop duties while Lowrie was shelved, and will return to a backup role.
Andrelton Simmons, SS - activated from the 15-day DL
Impact: Simmons earned the regular shortstop job in Atlanta at the beginning of June when Tyler Pastornicky was sent to the minors due to defensive struggles. Simmons performed well, hitting .296 with three home runs and 15 RBI in 33 games before he broke the little finger on his right hand July 8. The 23-year-old now reclaims his starting role and could have some value in deeper leagues. He isn't likely to hit for much power based on his minor league history, but he has some speed and may hit for a decent average.
Lonnie Chisenhall, 3B - activated from the 60-day DL
Impact: The Indians' third baseman was sidelined for more than two months after undergoing surgery to repair a fractured bone in his right forearm. The 23-year-old Chisenhall became the Tribe's regular third baseman midway through last season and finished the 2011 season with a .255 average, seven home runs and 22 RBI in 66 games. He failed to make the team out of spring training this year, but looked sharp between his promotion near the end of May and the time of his injury June 29. He returns to a .278 average, three home runs and nine RBI through 25 games. He should get regular playing time the rest of the season, so fantasy owners should want to take notice.
Darin Ruf, 1B - recalled from Double-A Reading
Impact: Ruf had a monster season at Double-A Reading, as he crushed 38 long balls, drove in 104 runs and posted a nice .317 batting average over 139 games. Those numbers were good enough to earn him the Eastern League's MVP honors and a call-up to the big leagues. While he isn't expected to be an everyday player the final weeks of the season, he could still get two or three starts a week at first base or in the outfield. With his offensive potential, he could be an asset to fantasy teams in leagues that allow daily transactions.
Daniel Nava, OF - activated from the 15-day DL
Impact: Nava missed most of the last six weeks due to a sprained left wrist, but is now back in Boston's outfield mix. He'll have to compete with the likes of Ryan Kalish and Scott Podsednik for at-bats, but should still get a few starts a week. He returns to a .250 average, four home runs and 27 RBI in 67 games with Boston.
Denard Span, OF - activated from the 15-day DL
Impact: Minnesota's center fielder has returned to action after missing most of the last month with an injury to his collarbone. Span missed over half of the 2011 season due to injury, but was looking sharp this year before injuring the collarbone Aug. 12 while attempting a diving catch. He returns to a .286 average, 60 runs scored and 14 stolen bases in 109 games and should be in the lineup on a regular basis.
Gavin Floyd, RHP - activated from the 15-day DL
Impact: Floyd hadn't pitched since he left his start Aug. 26 with a strained right elbow. The veteran righty has been putting up his usual so-so numbers this year, as he returns to a 9-9 record and a 4.55 ERA. His decent 7.42 K/9 strikeout ratio makes it a little easier to digest his other numbers, but he has yet to show that he's capable of being more than a No. 3 starter.
Ivan Nova, RHP - activated from the 15-day DL
Impact: Nova has returned to the Yankees rotation after missing two-and-a-half weeks with inflammation in his right rotator cuff. Despite his high ERA (4.92) and WHIP (1.46), Nova did have some fantasy value in deeper leagues prior to his injury, thanks to an 11-7 record and a healthy 7.95 K/9 strikeout rate. It was originally stated that he would be relegated to the bullpen after his return, but manager Joe Girardi has penciled Nova in to start Saturday against Tampa Bay. Freddy Garcia is now the odd man out and will likely spend the remainder of the season in the bullpen.