Rotation decision a welcome change from the status quo for Washington Nationals

The assumption throughout this past week has been that Joe Ross would either be moved to the bullpen or sent down to AAA when Stephen Strasburg was ready to return. The 22-year-old rookie has been outstanding filling in while Strasburg has been on the disabled list, posting a 2.80 ERA, a 2.56 FIP, and a 47:4 strikeout to walk ratio in 45 innings. Still, Ross is a rookie, and we've seen over the course of the past two years that Matt Williams likes to give his veterans a lot of rope.

Doug Fister has apparently used up all of his rope for now. The 31-year-old veteran just hasn't had it this year. His sinker hasn't been effective this season. He's left a lot more balls up in the zone and hitters are squaring him up far more regularly than they did last season. This has led to a career worst 4.60 ERA. His identical 4.60 FIP tells us that the ERA spike isn't exactly a mirage.

Why has Fister struggled this season? Let's take a quick look at his batted ball numbers......

We'll note that the decline in ground ball rate is a two year trend. His ground ball rate last season was actually 5.4% lower than it was in 2013. He's now lost 6.9% off of his ground ball rate from last year as well. In 2014, he was able to overcome the dip to his ground ball rate in part because he simply replaced that bump with a lot of fly balls. While fly balls obviously leave the yard more often than other types of contact, they're also the most likely type of contact to be converted into an out. Here... Let's have a look at 2015 splits across the league by batted ball type.

Allowing more fly balls and less ground balls actually helped Fister in 2014, as he finished with a career best .266 BABIP. He allowed a career high 18 homers, but that didn't end up biting him because he allowed fewer baserunners than ever before (OK... slight exaggeration... his 1.08 WHIP ranked second to his 1.06 WHIP in 2011). The most important aspect of Fister's batted ball profile in 2014 was his career best 16.9% line drive rate, which was 3.2% below his career rate and 4.4% lower than it was in 2013.

What's killing Fister this season isn't that he's allowing a ton of fly balls. He's allowed just a slightly higher fly ball rate (+1.1%) than he did in 2014. The problem is that his line drive rate has shot up to a career worst 22.7%. While it's a career worst rate, it's an awfully lot closer to his 2011-2013 line drive rate than his outlier 2014 rate. Since his fly ball rate has remained roughly the same, that spike in his line drive rate has come at the cost of ground balls. As the graphic above points out, batters around the entire league are hitting .643/.637/1.033 when they hit line drives, so this is a recipe for disaster.

We've seen Matt Williams faced with the choice of changing the role of an underperforming veteran in the past a few times. We saw it with Rafael Soriano late last season. We've seen it with Ian Desmond and Wilson Ramos throughout the course of the 2015 season.

• In the case of Soriano, Williams eventually made the change to go to Drew Storen as his closer and shipped Soriano off to a middle relief/setup role. It probably took a bit longer than many of us would have liked, but he got there.
• In the case of Desmond, he's stuck with him longer than a lot of people would have liked. To be fair, he hasn't had the rest of the infield healthy long enough so that making a change (presumably to Danny Espinosa) has really been a long-term option until recently. Espinosa had to play elsewhere for such a long stretch because of the injuries.
• In the case of Ramos, Williams started to show more of a quick hook. When Ramos had a miserable slump throughout July, Williams started rotating Jose Lobaton into the lineup a lot more regularly.

Sure... We've also seen this happen with Adam LaRoche, who went through the occasional extended slump last season, but remained in the lineup. We may end up seeing this become an issue with Jayson Werth and Ryan Zimmerman, who have each missed two months due to injury this season but haven't performed very well when in the lineup.

It's a fine line. As I mentioned when we talked about Wilson Ramos the other day, the major league baseball season is a marathon filled with peaks and valleys. Hitters will occasionally go into extended slumps. Many of them will also have a few of those one or two week stretches where they're completely locked in and the baseball looks huge coming out of a pitcher's hand. Sticking with veterans happens for a reason. They have established baselines at the level that give us a better idea of what they're capable of.

At the same time, age and injury eventually catch up to everyone. Those baselines that veterans have established give us a good guideline to determine what we should expect out of a player, but there are going to be several points in each player's career where that baseline is going to change. Sometimes we're going to expect that production to improve, which is usually at a time when that player is hitting their prime. Sometimes we're going to expect it to decline, which is generally either going to be accompanied by either an injury or age-related decline... The bat slows down; A pitcher loses a tick or two on his fastball; The wheels start to turn just a bit more slowly.

It had to be a tough decision for Williams to remove Fister from the rotation, but it looks like the right call. There are times when it's best to stick with the veterans and let them work things out. With two thirds of the season in the books and the Nats in a dogfight for the NL East crown, now doesn't look like one of those times. Ross is performing better, so it's good to see the Nats decide that they're going to keep giving the kid the ball every fifth day.