On Friday, Sept. 19, 2014, Adam Jones rested.

His Orioles, playing the Red Sox in the first game of the final regular-season series at Camden Yards, were still in the hunt for postseason home-field advantage and were battling the Angels for the best record in the American League. But manager Buck Showalter had given his instructions following the O's 6-1 win over the Blue Jays the Wednesday night before: Thursday was an off day, and Jones was to sit on Friday. Show up at 5:00 p.m. Stay off his feet. Relax. For the first time all season, the center fielder was to get a 36-hour break.

"Yeah, I remember I had a day off last year, obviously against my will," Jones says. "But the next day, I just felt so good. Obviously, my body needed that day off and it was pretty cool to get it."

Jones is no stranger to a full workload. He played 162 games in 2012, 160 in 2013 and 159 in 2014. But the amount of players logging those kind of numbers has decreased in recent years. Last season, only four players in Major League Baseball played 162 games: Giants' right fielder Hunter Pence, Braves first baseman Freddie Freeman, Rays' third baseman Evan Longoria and Royals' shortstop Alcides Escobar. In fact, in 2014, only 40 players appeared in 154 games or more, which is the lowest number in 20 years. But it's not because of injuries. It's because baseball is finally realizing the value of rest.

"I think we're getting more analytical about this and asking ourselves how we can preserve these players over the course of a season," says long-time Dodgers trainer Stan Conte. "If a guy does great playing four games in a row but doesn't do well on the fifth day, why are we playing him when we have a fresh guy on the bench who could be better? I think we definitely see a decrease in performance when people get fatigued. And then maybe you get injuries after that."

There's no study that concretely correlates fatigue with a decrease in performance or injury in baseball position players. Nor is there one that can tell a manager whether his star at 80 percent is better than one of his replacements at 100 percent. But logic says that if a player is tired, he won't play as well and may be at a higher risk of getting hurt.

Take outfielder Matt Kemp. The then-Dodgers outfielder played more than 155 games for four consecutive years, from 2008 through 2011, including a full 162 in 2010. Then, he spent two seasons on and off the disabled list. "Kemp had a whole rash of injuries," Conte says. "Was it related to that streak? I don't know. But intuition and logic say, well, I went really, really hard, and then I fell down, so there may be a relationship there."

The number of players who have played 154 games or more in a given season (strike-shortened seasons removed).

It's a concept other sports have embraced for years. In February, the Pirates made news because their general manager, Neal Huntington, and manager, Clint Hurdle, took note of the NBA's Golden State Warriors cutting the minutes of All-Stars Stephen Curry and Klay Thompson in an effort to maximize their performance. Hurdle mentioned it in response to a query about potentially factoring in more rest for workhorse centerfielder Andrew McCutchen. "They're actually playing less, and they're playing better collectively as a group," Hurdle said of Golden State.

But baseball isn't basketball. The pace of the sport is slower, with considerably fewer recovery days built into the schedule. Minutes are less intense, yet the games are longer and not played within a finite amount of time. Removing a player from a ballgame after six innings -- which could easily be three hours into the game -- just isn't the same as cutting a power forward's minutes from 42 to 33.

"Ask any everyday player, and they'll tell you playing six innings isn't a rest," says Red Sox manager John Farrell. "If they're getting time off, they want off the field completely. In our game, it's not minutes-related."

Most players, though, don't want off the field at all. 162 games is a marker for position players just like 200 innings is the goal for every starting pitcher, and staying on the field is a point of pride. Nowhere is this truer than in Baltimore, where the memory of Cal Ripken Jr. is still fresh. "There's something in me, I show up, I want to play," Jones says. "Even if I wake up in the morning and think, wow, I really don't want to play today, by 3 or 4 p.m. the adrenaline kicks in and that feeling goes away and I'm good to go."

But leveler heads are prevailing. Pence, who is the only player in recent years to log back-to-back seasons at 162 games, may argue with Giants' manager Bruce Bochy about sitting, but in the end, he'll do whatever his skipper tells him to do. Pence actually would have appeared in only 161 games last season, if not for a pinch-hit appearance in the second-to-last game of 2014. Prior to the game, Bochy had decided to rest Pence, which brought his streak of 331 games started -- the longest in MLB at the time-- to a halt.

Most managers agree that playing 162 games just isn't practical. Braves skipper Fredi Gonzalez admits he saw Freeman dragging at times over the course of last season, and may adjust his game total in 2015. "Of course, you can go stand out there for nine innings and get four at-bats but are you really being productive?" Gonzalez says. "You can't be."

Yankees manager Joe Girardi also closely monitors his older roster. "I've had to think about this a lot over the last four or five years because of the age of the players we've had on this team," he says. "There is that pressure of when to rest them, how much they need, and you have to deal with the critics asking why. But when you have a plan, you stick to it and say, 'This is what it is.'"

The plan, across baseball, is to reduce fatigue to increase performance, in every way possible. Players are wearing heart-rate monitors to measure fatigue. Teams are counting trips on and off the field, trips around the bases, walks to and from the batter's box and adding them to a player's total workload. They're hiring sleep specialists, nutritionists and chefs, and changing flight schedules to fly the day of the game instead of overnight. Teams will skip infield, or be allowed to take batting practice in shorts, simply as a mental reprieve. And they will be giving players more days off, many of which will be before or after a scheduled off-day, in order to give a player two full days of rest.

"We know players want to play, but the people who are running the organization have to look at the bigger picture rather than the individual," Conte says. "There have to be adults in the room who say, 'You are going to do this for the better good of you and the team, to increase performance and win more games.'"