Injuries are often reported as time lost, usually as a range of days, weeks, or even months. As the clock ticks down toward Opening Day with the sledgehammer tocks of a Jack Bauer-style clock, baseball players are learning that while there’s no clock during the game, there may as well be one hanging on the wall of the training room. The steadily moving arrow of time is not the key, however. Instead, it’s the gap between “now” and “healed.” The trouble is, that time span is different for everyone.

It’s even harder to evaluate during spring training. “The guys are all at different stages. Some are coming off winter ball and are tired. Some are rested, and not ready for a full load yet,” one trainer explained. Injury management is in many ways not unlike scouting. It takes years of training and experience to make the required decisions, all of which go into both treating an athlete and estimating his recovery time. “The hardest part is knowing there’s a hard deadline. Opening Day is what all these guys are shooting for once they’ve made the team, and getting the team as close to 100 percent on that date puts pressure on both them and us,” he explained. “It gets the rehab a bit tighter. We push to make sure that four weeks means four weeks, or that four to six is closer to four if it’s not going to put a guy in a bad spot.”

With time becoming tight, teams are looking closely at the injuries they have, and working hard to prevent any new ones. With pitchers, it’s more difficult; not only do they need to be physically able, but getting them up to speed and building their stamina is a big part of spring training. “Even missing a day or two sets them back,” the trainer explained.

The case of Cole Hamels is a great example. Hamels felt tightness in his pitching elbow and was examined by the team physician. The finding was simple inflammation, away from any major structure, and likely the result of simple wear and tear. He’ll be back to throwing within the week, but even the small deviation from plan puts his Opening Day status in jeopardy. “Does it matter if [Hamels] starts on April 5? Not really, not in the long term,” said one AL executive, “but you take a case like this where it’s the ESPN game, and they’re coming off a [World] Series, and yes, it starts to seem like it matters.” In a long season, a focus on any one date can be disastrous. If Hamels is back soon after Opening Day and makes his 30-something starts, it shouldn’t matter if he takes the ball on that night or in that opening series-but that deadline still hangs there, ticking like a bomb.

The same could be said for Johan Santana. While Mets fans and fantasy owners panicked early in spring training, the results that he’s put up since experiencing problems with his elbow have calmed the storm. Soreness is one thing, but pain and swelling are another. With a history of bone spurs, there is always a concern that this could recur with Santana (or Ervin Santana, who’s had problems as well). The Mets have been comfortable with the results of both his side sessions and his first couple of times up on the mound. Much was made of the fact that the Mets didn’t send Santana for an MRI, but those images aren’t gospel; in fact, they’re often inconclusive.

The World Baseball Classic has made for a lot of spring ink, but not a lot of significant injuries; nevertheless, “Classic-itis” is a term we’ve heard since teams were being selected. While Chipper Jones (oblique), Dustin Pedroia (abdominal strain) and Ryan Braun (ribcage) have been injured during the Classic, none of those injuries are significant. Jones followed his standard pattern, trying to come back too quickly and re-injuring himself, but with time to heal up before the season starts, he and the other two should all be in the Opening Day lineups with no deficits. Braun didn’t even miss a game for the ill-fated Team USA. David Wright is another player of note injured during the Classic; he fouled a ball off of his toe, and while he was initially worried that he may have broken it, he’s just going to miss a pedicure or two while the cracked, painful toenail grows back in.

Perhaps the most serious injury to occur to anyone on Team USA was that of Kevin Youkilis, who came out of the tournament with a sprained ankle. He showed no real damage, and is expected back as soon as this week; a couple of extra weeks should have him at or near 100 percent, which gives the Red Sox some leeway with third baseman Mike Lowell, who is more of a question mark than, say, Chase Utley is. Utley has played more like a man who’s been resting since we last saw him after the World Series, rather than one who underwent a major surgery and months of hard rehab; he’s moving well and showing no ill-effects at all. With Utley and Lowell (or Alex Rodriguez), the issue is less about getting them back than it is about keeping them back. It looks as if Utley and Lowell will be ready on or around Opening Day, with Rodriguez ready as soon as April 15, though May 1 is a more likely date.

The news isn’t so good for Joe Mauer, because after a back problem and kidney surgery, he’s having more back problems. The two are discreet and only related by symptom-lower back pain-with the swollen back joint exacerbated by squatting, precisely what the Twins insist on having Mauer do. Mauer could DH once these symptoms clear up, but catching is going to put so much pressure on his back that several sources think this will be the injury that finally pushes the Twins to get the gear off of their best hitter.

Remember too that there are some injuries that play into a team’s hands or involve other circumstances. Teams will consider roster space and their schedule when making moves. B.J. Upton is caught up by all of these complications, with a crunch of players out of options and a schedule that takes the Rays to two cold-weather cities during the first week. While he could play on Opening Day after recovering from shoulder surgery, circumstances are such that he’s likely to start out on the DL. Try not to let these kinds of factors and their unexpected outcomes take you by surprise when it comes to managing your own roster.

A version of this story originally appeared on ESPN Insider Insider.