Diamondbacks' Shelby Miller: Could make season debut Monday

Miller (elbow) completed a 40-pitch bullpen session Tuesday and could assume Matt Koch's spot in the Arizona rotation when the latter's next scheduled turn comes up Monday in Miami, Zach Buchanan of The Athletic Arizona reports.

Koch was tagged for five runs in 5.2 innings while taking the loss Tuesday against the Angels, inflating his ERA to 6.10 over his last seven outings. Though he's been a serviceable innings eater since replacing the injured Taijuan Walker (elbow) in mid-April, Koch's lack of strikeout stuff and flyball-heavy tendencies don't give him nearly the upside nor the stability of Miller, who has three seasons of sub-4.00 ERAs on his resume and whiffed 10 batters over 6.2 innings in his most recent rehab start at High-A Visalia last weekend. Since Miller only threw 81 pitches in that outing, it's possible the Diamondbacks may want him to exceed the 90-pitch threshold in another minor-league start before returning to the big club, but his reinstatement is imminent nonetheless. Once he's activated, Miller may need to perform well right away to bolster his case for sticking in the rotation, as Robbie Ray (oblique) isn't far off a return from the DL either.