After making it all the way to the World Series last year, the Arizona Diamondbacks haven't exactly followed things up the way they would have expected to. Their 37-38 record has them sitting nine games behind the Los Angeles Dodgers in the National League West, but they could soon get a boost in the return of their ace Zac Gallen.

Gallen ended up on the injured list back on May 31st with a strained right hamstring, and he has been working his way back ever since then. The good news is that it sounds like he is making some real progress in his quest to get back on the mound, but the bad news is that he is still without a true return date, which has kept his rehab status cloudy, even amid these positive updates.

“Gallen threw a 31-pitch bullpen session on June 11, a 37-pitch session on June 14 and threw a simulated game on June 18. He is scheduled to throw one more simulated game either on June 24 or 25. After that, it’s possible he could be activated.” – MLB.com

Diamondbacks hoping Zac Gallen can return as soon as possible

Arizona Diamondbacks starting pitcher Zac Gallen (23) pitches in the first inning against the New York Mets at Citi Field.
Wendell Cruz-USA TODAY Sports

Gallen has quietly emerged as one of the top starters in the MLB over the past few years, and he was instrumental in Arizona's run to the World Series last year. He got off to another strong start this season (5-4, 3.12 ERA, 60 K, 1.15 WHIP) before he hit the injured list, and the hope is he can pick up right where he left off right when he comes back.

This is a situation definitely worth monitoring, partly because of how much the starting rotation has struggled without Gallen. Only Brandon Pfaadt has an ERA under five runs, with Ryne Nelson and Slade Cecconi both having ERAs over five, and Jordan Montgomery and Tommy Henry having ERAs over six. If they want to find their way back into the playoffs this year, those figures are going to have to improve.

The fact that Gallen is throwing again is encouraging, but ideally, you'd like for him to have a return date set in stone. Still, it seems like he could realistically be activated before the end of June without even having to make a rehab start, which is huge because the quicker he gets back, the better off the Diamondbacks starting rotation will be.

As a result, the next few days are going to be incredibly important for Gallen to see how his body responds. If he continues to pass these tests in flying colors, he'll be activated before you know it. But until then, it's worth keeping a close eye on his status just to make sure that nothing pops up that will delay his return to the majors.