The veterans: Delgado, Perez, Reed and Ziegler
Likely to be the first inked in to bullpen spots for 2015: none have minor-league options left, and they occupied the top four spots last season in terms of innings pitched (246.1 total IP, close to half of all relief work (507 IP). As such, most roles are probably fairly well-defined. Randall Delgado will be long relief; Oliver Perez our front-line left-hander, and Addison Reed the closer. Whether that's the best job for each is a topic for discussion. In particular, Reed's performance as closer last year wasn't impressive: six blown saves plus three losses in non-save situations. We lost 18 times last year when leading or tied after eight, almost 50% more than NL average for the other teams (12.1)
A bigger question-mark may be Brad Ziegler. We'd like to have him back in his roaming "fireman" role, putting out rallies wherever needed with his GIDP skills. But Brad spent the second-half of the season dealing with injuries to both chest and knee, causing an early end to his campaign last year. He had an ERA after the break of 6.27, was shut down completely for the Diamondbacks' final 22 games and underwent arthroscopic microfracture surgery on his knee in September. At the time, it was said that "being ready for the start of the 2015 season may be a stretch," so proving his health will be the first thing.
The TJ rehabbers: Hudson, Hernandez and Reynolds
This trio all but missed the 2014 season entirely, save Daniel Hudson making it back for a token (albeit still very welcome) 2.2 innings in September. Hudson will certainly start 2015 in the bullpen, but it's still uncertain if that will be his position long-term. The team has said they would "like to best utilize him in a way that we can get the most out of him." That would generally be starting, which is also Hudson's goal: but after two Tommy John procedures, would that, literally, be chancing Daniel's arm? There's also the question of how to make the transition: there's a big gap between bullpen outings and being expected to go six or more innings as a starter.
With David Hernandez and Matt Reynolds, the process should be a little more straightforward, since it was the first Tommy John surgery for each man. By the time pitchers and catchers report,. Reynolds will be close to 17 months past his operation in September 2013, so should be more than ready. However, Hernandez will have enjoyed significantly less rehab time, going under the knife at the start of April 2014. That was a week after Patrick Corbin, and it was already announced Corbin likely won't be back until June. While as a reliever, Hernandez might return somewhat quicker, expecting 100% performance at exactly a year after surgery seems optimistic.
The fresh faces: Marshall, Stites and beyond
As we already documented, only Thatcher posted a better ERA for the Diamondbacks last season than Evan Marshall. This, and his shiny K-rate, should get him a spot in the 2015 bullpen, and could perhaps put Marshall first in line for a shot at the closer's position if Reed stumbles. Particularly if Ziegler is unavailable, Marshall may start the season as Reed's primary set-up man, a position he occupied in September. Stites, often thought of as Reed's heir apparent and the same age as Marshall, didn't have such a successful 2014, with a 5.73 ERA in 33 innings, and will need to demonstrate improvement if he's to have a future with us beyond middle relief.
Of the prospects who might break through in 2015, Jake Barrett is perhaps the most likely, despite his very young age - he turned 23 in July, but still put up a 3.09 ERA between Mobile and Reno. He probably needs to get his walk rate (4.4 per 9IP) down a bit, however. Jimmie Sherfy is another name we may see. But if you're looking for a sleeper, what about Enrique Burgos, who got more than half his 2014 outs by the K at High-A? Double-A likely beckons as a result, and if he does as well there, his name will be on the short-list. Silvino Bracho's K-rate was even higher (70 in 43.1 innings!) for A-ball South Bend, but 2016 seems a more realistic time-frame.
There isn't as much of a log-jam in 2015 as in previous years. The herd of relievers has been thinned considerably since this point last year, with the departures from the 'pen of Josh Collmenter, J.J. Putz, Will Harris, Joe Thatcher and Eury de la Rosa, for various reasons and with sharply-differing senses of loss. The return of our TJ trio should help, but there's a non-zero chance that one or more of them will experience further elbow problems. We'll certainly need more than seven arms: last season, we used no less than 19, and those outside the top seven threw 28% of our bullpen innings, so about the equivalent of two full-time relievers.
The Diamondbacks endured a relief ERA of 3.92 last year, which was the third-highest in the National League - only the Rockies allowed a higher OPS. While the starting rotation has, understandably, been the focus of most concern, the bullpen will also need to be significantly better, if the team is to make headway towards getting back to .500, and beyond. While that revolves around closer Addison Reed, every zero is important, and we'll need improvement all the way from front to back.