To rest or not to rest? Gabe Kapler wants to keep Phillies outfielders fresh, productive

On a lazy spring-training morning earlier this month at Spectrum Field – as lazy as a spring-training morning gets when Gabe Kapler is managing, that is – music filled the Phillies clubhouse. Rhys Hoskins stood at his locker and spoke over the sound. The music was a country song, Garth Brooks' "Friends in Low Places" – a crowd-pleasing singalong, popular in the early 1990s, about a man who can't let go of the past – and it offered a stark juxtaposition to the substance of Hoskins' words.

The Phillies will have four outfielders who, in theory, will be worthy of being in the starting lineup: Hoskins, Odubel Herrera, Aaron Altherr, and Nick Williams. Kapler has said he plans to rotate the four so that each of them will play roughly 145 games. This, he believes, will keep them healthier and fresher and, presumably, more productive than if he wrote three of their names on his lineup card 162 times.

"The game is changing," Hoskins said. "That's been pretty apparent the last couple of years in baseball. That old-time way of thinking, I don't think it's completely gone away, but it's starting to mesh with some of the new thought around baseball. I think one of those new thoughts is what Gabe has stressed: flexibility."

Does that flexibility, that willingness to play an unfamiliar position or to work a regular day or two of rest into each week, actually help a major-league player and, in turn, a major-league team over a full season, though? Take Ryan Howard in his prime, from 2006 through 2009, when he averaged 156 games and 50 home runs a season and his cumulative on-base-plus-slugging percentage was .967. Even if he were mentally and physically fatigued for a few of those games, isn't a tired Ryan Howard still better than, say, a well-rested Greg Dobbs? And how often is a manager going to tell Howard to take a seat if Howard, either because he's adhering to that tried-and-true obligation that "you're supposed to play every day" or because he felt good while taking his cuts in BP, is lobbying to play?

Under Kapler and general manager Matt Klentak, the Phillies have embraced analytics with the zeal of a skeptic who has been born again, and there is, in fact, statistical evidence to suggest that a few extra days off for a player can benefit him and the team as a whole. In a 2013 article for Baseball Prospectus, Russell A. Carleton examined data from 2003 through 2012 to try to determine how fatigued players get and how much a routine day or two of rest might or might not help them. He found that playing every day did have an attritional effect: "The number of games that a hitter had played in the previous seven days … had an across-the-board negative effect on all sorts of hits (singles, doubles/triples, and home runs) and increased the number of outs in play that a hitter made."

More, a hitter who played five games every seven days had, on average, an on-base percentage that was three points higher than a hitter who played seven games every seven days. "Over 600 plate appearances, it's about an extra two on-base events, and that's worth a run or so," Carleton wrote. "Over multiple lineup spots, it can build into a lost win really quickly. A manager who does not rotate his players a bit may be bleeding away value and not even realizing it."

Carleton's study is nearly five years old; the notion that rest is a tangible good isn't all that new. Consider: At least one National League player had appeared in 162 games every season from 1996 through 2014. But when the Phillies' Freddy Galvis and the Reds' Joey Votto played all 162 last season, it marked the first time that any NL player had done so since that 18-year stretch. And given how late the Phillies were to baseball's analytical revolution, it's easy to overstate just how radical Kapler's ideas really are, relative to how other teams have done things.

Managers such as the Cubs' Joe Maddon and the Dodgers' Dave "Doc" Roberts have used similar approaches, and their philosophies have influenced Kapler, which shouldn't be surprising. He played under Maddon while the two were with the Tampa Bay Rays, and he worked with Roberts in the Dodgers organization.

"One of the things that Joe and Doc did so successfully is giving these guys a chance to succeed and put up numbers on a day-to-day basis," Kapler said. "It's the same way you approach a relief pitcher: You don't bring him in against someone who's likely to kick his ass. You bring him in against a guy he's likely to dominate."

As part of Kapler's applying this thinking to the Phillies lineup, Hoskins, who has been a first baseman for most of his career, will play left field. That shift afforded the Phillies the opening to sign a high-on-base hitter, first baseman Carlos Santana, but it will put, one could argue, a double burden on Hoskins: He might get fewer at-bats than he might want while playing a less-comfortable position. But then, Hoskins himself dismissed such an argument.

"We're going to be given an opportunity to be healthy and strong as we get to the end of the season," he said. "It's detrimental to the team if you take your at-bats out to the field or if you make an error and take it with you to the plate. If I can't do that or if someone on the team is incapable of separating the two, we're going to be in trouble."