- Date of birth: November 2, 1990
- 2017 line: 1 game, 0.0 IP, infinite ERA, 0:1 K:BB
- 2017 value: N/A
- 2017 salary: minimum
- SnakePit rating: 3.02
Koch came into the ninth inning on August 22 against the Mets in New York, with a 7-1 lead. He went walk, single, RBI double and was then lifted. Andrew Chafin allowed both runners inherited from Matt to score, before the six-run lead became a two-pitch save for Fernando Rodney. Koch was optioned back to Reno and didn’t appear again. He therefore became the first Diamondback ever to record an infinite ERA - allowing one or more earned runs, while failing to retire a batter. He was also the first NL reliever since Bryan Harvey of the 1995 Marlins, to allow 3 or more earned runs in a season, without retiring a better.
Uh... Well done, I guess? Because that is pretty hard. Less then fifty players in recorded baseball history have had an infinite ERA, so it’s rarer than a no-hitter. It was also quite surprising, because Koch had performed very respectably in 2016, with a 2.00 ERA over 18 innings, including a pair of decent spot-starts at the end of the season. His 2017 was derailed by injury, which caused Koch to miss most of the first half, and he had a hellacious (Game Score of -13!) start on August 5, allowing 11 earned runs over two innings. That helped balloon his minor-league ERA for the year to 7.71 over 12 starts, though he did finish with a start of seven shutout innings in Reno.
It is possible that the Diamondbacks might be looking for a long reliever in 2018. That’s a role which was largely filled by Randall Delgado this year. But Delgado had a 4.30 ERA in relief, and is in his final year of arbitration, so will be relatively expensive. Koch has been a starter for most of his minor-league career (81 starts in 122 appearances), so might be a cheaper candidate for the position. But he will first have to prove he can be a great deal more effective than he was in 2017, though it’s hard to say what impact the (somewhat vague) injury played in his struggles. Otherwise, he’ll be quite some way down the depth chart for both the Arizona bullpen and rotation.