Where did the Nationals go wrong?

There have been a lot of heads hanging around the Nationals this season. Greg Fiume/Getty Images

I got burned badly this year by the Washington Nationals, though thankfully I'm not alone. With the defending NL East champions coming off a 98-win season with a young rotation that looked to dominate again, I predicted they would represent the National League in the World Series -- after winning more than 100 games in the regular season. On the backs of Bryce Harper and Stephen Strasburg, the Nats were supposed to fly high above the Braves and Phillies, then skate through the playoffs.

The Nationals are now well under .500 and closer to the Marlins than the Braves. With a nod to the Phillies and their $160 million payroll, the Nationals have been the league's biggest disappointment. What were the factors that contributed to their failure?

Gio Gonzalez regressed

Gonzalez finished third in NL Cy Young voting last year, posting a sterling 2.89 ERA with an NL-best 21 wins. It was not his first brush with success. In the two preceding years with the Athletics, he had posted 3.23 and 3.12 ERAs in 200-plus innings. What we didn't see last year, which we are seeing this year, were home runs. In 2010 and 2011, in the pitcher-friendly confines of the O.co Coliseum, between 7.4 and 8.9 percent of fly balls surrendered were home runs. ESPN's park factors rated the O.co Coliseum 28th of 30 ballparks in homer-friendliness in 2010 and 26th in 2011. Nationals Park rated 11th last year and 20th this year.

We should have expected more home runs moving from Oakland to Washington, D.C., but they didn't appear last year. Gonzalez surrendered nine total, below 6 percent of fly balls. They returned this season, though, as he already has allowed 14, nearly 12 percent of fly balls. His ERA sits at 3.57.

Shaky back of the rotation

Rotation depth is one of the more underrated aspects of a successful baseball team. In 2012, the Nationals had Ross Detwiler and Edwin Jackson at the back, posting a 3.40 and a 4.03 ERA, respectively. This year, Detwiler was worse (4.04 ERA) and eventually had to go on the shelf with a herniated disk, ending his season after 13 starts. Dan Haren has been abysmal, sitting on a 5.14 ERA as of Thursday.

Worse middle relief

The 2012 Nats had three relievers (minimum 10 innings) post an ERA above 3.03: Tyler Clippard (3.72), Henry Rodriguez (5.83), and Chien-Ming Wang (7.59). The addition of Rafael Soriano was supposed to increase the bullpen depth, but five guys have ERAs above 3.40: Craig Stammen (3.41), Rodriguez (4.00), Ryan Mattheus (5.82), Drew Storen (5.95), and Zach Duke (8.31). Relief pitchers are remarkably volatile on a year-to-year basis, but you have decent odds if you have guys who strike hitters out in bunches. The 2012 bullpen got batters to whiff on 25 percent of swings, the eighth-highest rate among all 30 bullpens. This year's squad has induced whiffs at a 23 percent rate, the fourth-lowest rate. Fewer whiffs means more balls in play. More balls in play means more hits.

Perhaps some bad luck is involved, as well. The pen has compiled an aggregate .310 batting average on balls in play (eighth-highest in the majors) compared with .279 last year (fourth-lowest).

Adam LaRoche regressed

LaRoche had a career year in 2012, posting an adjusted OPS of 127 (100 is average), the second-best mark of his career. He set a career high with 33 home runs and ranked as the third-best-hitting first baseman in the National League among qualified hitters, going by weighted on-base average (wOBA).

The takeaway, looking at his stats, is that he is simply not making good contact with baseballs on a frequent basis. Both his isolated power (slugging percentage minus batting average) and his batting average on balls in play are down. His .185 ISO would be his worst in a full season, and his .271 BABIP is 35 points below his career average. Hitters, unlike pitchers, have a great deal of control over their BABIP, so this isn't something entirely random.

Denard Span has been a flop

Nationals outfielders in 2012 combined for a .328 wOBA, just a shade above the major league average of .327. This year, it has dropped to .313, below the league average of .323. The difference in wOBA is worth about 23 fewer runs.

In the offseason, the Nationals acquired Span from the Twins, pushing Harper from center field to left field as they waved goodbye to Michael Morse. From left to right, last year's adjusted OPS went 113/120/126. This year, it is 139/89/145. Can you tell which doesn't belong?

There have been some other minor differences, as well, such as slightly less production from Ryan Zimmerman and Ian Desmond, and you can make the case that they have been worse defensively, as well. The bench has been terrible, with Roger Bernadina, Tyler Moore and Chad Tracy all hitting under .200 and Steve Lombardozzi posting a worthless .580 OPS. After a hot April, Harper got hurt and hasn't been the same. But the above are the glaring reasons the Nationals have failed to live up to the lofty expectations. By no means does this mean they can't surprise us all again in 2014, but, at least for this year, their playoff aspirations are gone. Baseball Prospectus gives them a 0.4 percent chance to reach the postseason, almost all of it related to winning the second wild card.

Bill Baer writes about the Phillies at Crashburn Alley and is a regular contributor to the SweetSpot blog.