Not as much as you might think.
There are two statistics that Phillies fans and Phillies general manager Ruben Amaro Jr. point to as proof that a healthy Howard could change the team's fortunes. As reported by Dennis Deitch of the Delaware County Daily Times:
- Phillies record in 2012-13 with Howard in the starting lineup: 77-63
- Phillies record in 2012-13 without Howard in the starting lineup: 77-107
A simple calculation shows that 77 wins out of 140 games played yields a .550 winning percentage, which over a 162-game season would yield 89 wins.
In 2013, 89 wins would have left the Phillies one win shy of the playoffs, but such a season would have been a lot more fun to watch than the 73 wins they actually posted.
Unfortunately, the simple statistics above are pretty much undone by the more complicated statistics that follow.
Dan Szymborski of ESPN.com set forth at length the reasons why Howard's five-year, $125 million contract extension was the worst contract in baseball history.
And Szymborski's analysis portends dark days for Howard and the Phillies.
For starters, Szymborski noted that "Howard's top comps are not a pretty group—Carlos Pena, Richie Sexson, Greg Luzinski, Jim Gentile, Mo Vaughn and Cecil Fielder—and these are all players who aged poorly."
Then Szymborski ran the numbers with his proprietary ZiPS system to project Howard's batting average/on-base percentage/slugging percentage lines. Here is what came out:
In a 2013 Philadelphia environment, ZiPS projected Howard's 2013 season at .243/.333/.487 when his deal was signed. Before the 2011 season, the 2013 projection had dropped to .241/.325/.472; fast-forward another year and his 2013 projection was .246/.328/.476; and before this season, he was projected to hit .242/.325/.463.
As Szymborski harshly but fairly put it, Howard's actual performance in 2013 (a slash line of .266/.319/.465) was "exactly what you would expect from a one-dimensional slugger in his early 30s in the middle of a normal decline phase for a player of his type."
Probably the most alarming part of Howard's drop-off is the plummeting power numbers. The following players slugged .465 or better in 2013: Torii Hunter, Nate Schierholtz and Pedro Alvarez. Only Alvarez qualifies as a power hitter of those three, and he hit .233 in 2013.
Fangraphs.com has the Phillies winning 74 games in 2014. Their projection is of course silent as to Howard's health or lack thereof in 2014.
But the idea that Howard has a healthy, productive season in him that could improve the Phillies by 15 games trends beyond statistical improbability and into practical impossibility.