Spring training had barely started for the Toronto Blue Jays and manager John Gibbons was already facing questions about next offseason, when sluggers Jose Bautista and Edwin Encarnacion could become free agents.
''You're happy for them, but it also kind of magnifies the importance of this year for us, because nobody knows what the future holds,'' Gibbons said. ''So let's take advantage of this year while they're here and then hopefully they hang around for a long time, but nobody knows.''
It was just last season that the Blue Jays won the AL East and returned to the playoffs for the first time since 1993, and already there's a sense that the clock is ticking.
Success in baseball can be harshly cyclical. A perennial contender can become an aging also-ran almost overnight. For some teams, the word ''window'' represents a foreboding reminder that the time to win a World Series is now - and the opportunity won't be there forever.
The Blue Jays want to build on last year's success, while the Detroit Tigers and Washington Nationals hope 2015 was an aberration. All three teams are trying to keep their championship windows open, and it isn't easy.
''At some point, some teams get into an all-win-now mode because they're right there,'' Tigers general manager Al Avila said. ''It's very hard to get into the playoffs. It's very hard to get into the World Series, much more even to win it. When you feel you have that chance, you've got to go for it.''
The Tigers have spent most of the past decade going for it, handing out expensive contracts to both their own players and incoming free agents - and aggressively trading prospects for stars. Detroit won American League pennants in 2006 and 2012 and AL Central titles every year from 2011-2014, but the Tigers are still without a World Series championship since 1984.
Last year, Detroit fell all the way to the bottom of the division, and with Miguel Cabrera and Justin Verlander both in their 30s and signed to massive long-term deals, it looked like the Tigers might turn into the AL's version of the Phillies. Philadelphia finished atop the NL East every year from 2007-2011 - and won the World Series in `08 - but the decline afterward was swift as its core of stars aged.
Detroit tried to avoid that by spending tens of millions of dollars this offseason. After signing Justin Upton and Jordan Zimmermann, the Tigers and owner Mike Ilitch are expected to begin the season with a payroll around $200 million.
While the Tigers were spending big, the Blue Jays were gearing up for another run at a division title, albeit without David Price, who went from Detroit to Toronto in a trade deadline deal last year before leaving in the offseason for Boston. The Blue Jays have control over Josh Donaldson through 2018 and Troy Tulowitzki through 2021, but Bautista and Encarnacion are in the last year of their contracts.
The Nationals, meanwhile, already lost a key player in Zimmermann, and Stephen Strasburg is due to become a free agent after this season. Bryce Harper, last year's National League MVP, should be the centerpiece of the lineup for a while, but after a disappointing 83-win campaign in 2015, the Nationals can't be certain what their roster will look like a couple years from now.
Still, new manager Dusty Baker isn't buying the idea that Washington's window could close soon.
''The window closes if you don't replenish the refrigerator,'' Baker said. ''I don't believe in that window unless you stand pat and don't do anything. Then that window will close. If you do it right ... you'll see the same organizations win for a long time.''
There are two obvious ways teams can try to keep the window open. One is by spending more and more money, like the Tigers are doing now, and like the New York Yankees have done for years. Big-budget teams have the luxury of bringing in free agents who can boost what might otherwise be an aging roster.
The other way to keep winning is through player development. The St. Louis Cardinals have won at least 86 games in each of the past eight seasons, even though they aren't really thought of as big spenders like the Yankees, Dodgers or Red Sox.
A player like Albert Pujols leaves, and St. Louis always seems able to replace him. The Cardinals won 100 games last year with Trevor Rosenthal, Carlos Martinez, Stephen Piscotty, Randal Grichuk and Michael Wacha making significant contributions. All five of those players are in their mid-20s.
Avila, who took over as Detroit's GM in the middle of last season after having been Dave Dombrowski's assistant, says the farm system is a priority for him.
''You cannot consistently win at the major league level by just signing major league free agents,'' Avila said. ''You have to sign and develop your own players, and that is going to give you the foundation for the future.''
What's difficult, though, is balancing the need for a strong farm system with the opportunity to win at the major league level. The Tigers have made their share of significant trades in recent seasons, sending younger players away in exchange for veterans who helped Detroit win those division titles.
What was left last year was an expensive team that went 74-87 - and afterward, the only way the Tigers could significantly improve was by spending more money. That approach is difficult to sustain, but in 2016, Detroit will take the field with a team that absolutely believes it can return to the top of the division.
The Tigers aren't letting their window close without a fight.
''Mr. Ilitch has always given us the resources to put the best competitive team on the field,'' Avila said. ''It's great to work for that kind of owner, because you'd rather do that than the opposite.''
AP Sports Writer Stephen Whyno contributed to this report.