What is the difference between the 15-day and the 60-day disabled list? Two things: The 15-day DL players are eligible to return earlier. Second, players on the 15-day DL count against the 40-man roster, while the 60-day DL players don't. That's about it.
Teams assign players to the 15-day and 60-day lists according to their individual needs and judgments. You cannot infer too much from a player's appearance on the 15-day DL. A player on the 15-day DL will not necessary return to action soon, or even before someone on the 60-day DL. For example, Troy Percival is on the Rays' 15-day DL. Don't expect to see him pitch again in 2009. Or ever.
It's important to periodically scan the injury reports to see who is rehabbing and ready to return versus those facing months of uncertainty. Many leagues provide a DL spot, which helps, but you still need to make tough choices. During the course of a season you have more injured players than DL spots. Sometimes you have to keep an injured star on your roster; sometimes you have to bite the bullet and let him go.
Players on the DL that are returning in the foreseeable future with good potential to contribute are for better. Players will uncertain futures, murky diagnosis or limited upside are for worse.
Brandon Webb, SP, Diamondbacks: Webb is making progress recovering from his shoulder injury. He may be ready for a rehab assignment later this month and a return after the All-Star break. The 2006 Cy Young winner should be stashed until then, whether or not you have a DL slot in your league. Even a somewhat diminished Webb is worth sacrificing a roster spot.
John Smoltz, SP, Red Sox: Smoltz is on schedule to return this month. He had good velocity and looked sharp in his minor league rehab starts. Expect the Red Sox to move a starter (Brad Penny?) to make room for Smoltz. They could also go to a six-man rotation for a while. Either way, Smoltz will get work. He is worth picking up in any league where he is available.
Rich Harden, SP, Cubs: Harden is close to returning from his latest injury, a back sprain. Harden's career has been brilliant at times, but unfortunately interrupted by trips to the DL. His career numbers are impressive: 45-22, 3.33 ERA, 1.22 WHIP and 665 strikeouts in 656.1 innings. Harden is on track to return next week.
Carlos Quentin, OF, White Sox: No doubt Quentin's foot injury hurt his performance before he finally gave in and went on the DL. Quentin hit .253 with 8 HR and a .961 OPS in April before crawling through May with a .196 average, 0 HR and a .536 OPS. Expect Quentin to return later in June and to benefit from the rehabilitation time.
Jose Valverde, RP, Astros: Valverde strained a calf muscle in April and has been on the DL since then. Valverde is finally showing some progress and may soon start a rehab stint in the minors. That could put him two weeks away from returning. He is certainly worth stashing until then. Valverde could easily notch 20 saves in the second half of the season.
Travis Hafner, DH, Indians: Hafner's shoulder still isn't 100%, even though he is playing minor league rehab games. Lucky for him he doesn't need to play the field. He could return to Cleveland soon despite the soreness. Hafner was hitting a productive .270 with a strong .910 OPS when he was sidelined.
Josh Hamilton, OF, Rangers: It's back to the DL for Hamilton. He has an abdominal strain that could knock him out for a couple of months. The Rangers are going to get a second opinion, so we should know more in a few days. Stash him for now, and pray for a better prognosis.
Joey Votto, 1B, Reds: An emerging star, Votto went on the DL last Saturday for personal reasons. The Reds are not providing any specifics or a timeline beyond the 15-day DL. Fantasy owners have no choice but to stash Votto, and tie up a roster spot, until more information is available.
Jose Reyes, SS, Mets: The Mets are hopeful that Reyes will return this Friday. Reyes has tendonitis in his right calf, so you have to wonder if Reyes will be himself when he's back. Can he steal? Will he try? The injury could bother him for an extended period.
Carlos Delgado, 1B, Mets: Delgado had hip surgery on May 19 and is still hobbling around on crutches. The 36-year old might not play again this season and is not worth stashing in any league.
Grady Sizemore, OF, Indians: Sizemore's elbow is still barking. It's looking more and more likely that he will need arthroscopic surgery. The bum shoulder has hampered Sizemore's ability to play defense. Sizemore was hitting only .223.
Conor Jackson, OF/1B, Diamondbacks: Jackson landed on the DL with Valley Fever, a lung infection common in the Southwest. Apparently Jackson has a severe case and could be laid up for weeks. Jackson was only hitting .182 when afflicted; so there is absolutely no reason to keep him on either a roster or a DL spot.
Tim Hudson, SP, Braves: Hudson been on the DL all season, recuperating from Tommy John surgery. He is targeting an August return. Even if that happens on schedule, I think that's a long time to wait for Hudson. Realistically, the most you can expect from Hudson is a good month of baseball at the end of the season. He's not worth stashing for that.
Jed Lowrie, SS, Red Sox: Lowrie is looking at a post All Star return from his wrist injury. He will probably get his job back from Julio Lugo, but he does not hit enough to warrant stashing him for another six weeks.
Jesus Flores, C, Nationals: Flores' May 9 shoulder injury was thought to be minor. It now appears much worse than originally diagnosed. The injury could end his 2009 season, which is a shame. The 24-year old catcher was off to a strong start: .311, 4 HR in 90 at bats and a .904 slugging percentage.