The acquisition of Mark Trumbo by Arizona is one that has both its upsides as well as its flaws. From the D-backs' perspective, it was clear they wanted to add power as it was something GM Kevin Towers has expressed repeatedly in recent months.
Against that backdrop, acquiring Trumbo makes sense as it fulfilled a clear desire. Towers pointed out in the press conference yesterday that while Trumbo has his issues getting on base, 30-homer guys who get on base are tough to find these days. He is right.
In 2006, there were 22 players who hit at least 30 home runs and got on base at least 35 percent of the time. Over the past three seasons, that number has fallen from 17 to 12 to just 6. Adrian Beltre, Miguel Cabrera, Chris Davis, Edwin Encarnacion, Paul Goldschmidt, and David Ortiz were the only sluggers to hit both benchmarks in 2013. Beggars cannot be choosers; Arizona was begging for another power hitter and took what the market presented with the lack of ideal options.
That said, there also are the issues with his offensive abilities. (And that's without even discussing his shortcomings as outfielder, which could be a problem in Arizona.)
Few can match his raw power, and few can match his inability to get on base. Over the past three seasons, Trumbo's .300 on base percentage is the fifth-worst of all batters with at least 1,500 plate appearances. Only J.J. Hardy (.298), Jeff Francouer (.297), Alcides Escobar (.294), and Darwin Barney (.293) have lower OBP's in that time.
His other indicators as a full-time player are a mixed bag of results. This past season, Trumbo nearly doubled his anemic 4.4 percent walk rate from his rookie year. Additionally, he has improved his selectivity by season in reducing his overall swing rate as well as the percentage of pitches he swing at outside of the strike zone. Despite those gains, his strikeout rate has digressed each season from 20.9 to 26.1 to 27.1 percent this past season.
Surprisingly, the rise in strikeout rate is not from chasing pitches out of of the zone. His issues come from problems making contact on pitches within the strike zone (see table).
The league average for miss percentage on pitches within the strike zone is 14.6 percent; Trumbo's 21.8 percent rate places him in the bottom tenth percentile. The issues is more pronounced when focusing on the outer half of the zone. Trumbo's wOBA has declined from .353 to .350 to .324 this past season on pitches within the outer half of the strike zone. His swing-and-miss rate on those pitches was 15.6 percent as a rookie and doubled to 30.1 percent in 2013.
Pitchers are well aware of Trumbo's abilities to punish pitches on the inner half. As a full-time player, Trumbo has a .377 wOBA against pitches on the inner half of the strike zone with a 22 percent swing-and-miss rate. On pitches on the outer half of the strik ezone, his wOBA drops to .324 and his swing-and-miss rate jumps to 24 percent. Most of his struggles on the outer half are centered around his continual struggles with breaking balls away.
The continual decline with pitches in the zone is concerning, as research by Bill Petti from Fangraphs has shown how the drop-off for out of zone contact begins to precipitously decline around ages 28-29. Trumbo turns 28 next month. If the current issues within the zone coincide with the drop-off in out of zone contact, Trumbo's future could be in for an unfortunate downturn much like that of fellow right-handed all-or-nothing sluggers Mark Reynolds and Richie Sexson before him.