|ARIZONA DIAMONDBACKS||SAN DIEGO PADRES|
|A.J. Pollock - CF||Manuel Margot - CF|
|Chris Owings - RF||Ryan Schimpf - 3B|
|Paul Goldschmidt - 1B||Wil Myers - 1B|
|Jake Lamb - 3B||Hunter Renfroe - RF|
|Yasmany Tomas - LF||Yangervis Solarte - 2B|
|Brandon Drury - 2B||Austin Hedges - C|
|Chris Iannetta - C||Erick Aybar - SS|
|Nick Ahmed - SS||Allen Cordoba - LF|
|Patrick Corbin - LHP||Clayton Richard - LHP|
Firstly, counter to what you may have heard, the D-backs do NOT have the best rotation ERA in the National League. This appears to stem from the stats on Fangraphs, but the number given there for the Mets (3.49) is a lot higher than the figures given on Baseball-Reference.com and MLB.com (3.08). The reason for the discrepancy appears to be a start by Robert Gsellman for New York on April 13: the game log tags him with four unearned runs, but Fangraphs says those were earned. As a result of those runs - which shouldn't actually count - the Mets' rotational ERA increases above Arizona on Fangraphs.
So, only the second-best ERA in the National League. Mind you, I think we'd all have taken that at the beginning of the season, though there are legitimate grounds for wondering how sustainable this is. FIP - fielding independent ERA, based on HR, BB and K's - is close enough to ERA. But the D-backs' starters have been perilously good at keeping the ball in the park.They have allowed 0.71 HR per nine innings; the next best NL team is sitting at 0.87 per nine. This is why xFIP, which adjust for a "normal" home-run rate, has the D-backs only 8th in the league. If the balls start flying out of the park as they should, our ERA is going to regress.
And tonight, we see Patrick Corbin, who has been the poster child for this. His xFIP is exactly double his actual ERA, at 5.62 compared to 2.81. A combination of his very poor K:BB ratio of 7:7 in 16 innings, and Corbin only having allowed one homer. Petco is probably a good place for that to continue, but I'd be a great deal happier if he started striking out a lot more people and/or walking fewer.