The good news is that Aaron Nola hasn't had any issues with his elbow that plagued him last season, causing him to miss the last half of the year. Unfortunately, Nola experienced some soreness in his back during his last start and will again wind up on the DL.
"Aaron experienced soreness in his lower back during his start on Thursday. After receiving treatment over the last few days, the symptoms improved, but he still felt some tightness during his side session yesterday [Sunday]. Our hope and expectation is that this will not be a lengthy DL placement and that Aaron will miss only one or two starts." - Statement by GM Matt Klentak.
Nola wound up giving up four earned runs in five innings of work in his last start, and is 2-0 with a 4.50 ERA in three starts this season.
The Phillies haven't made a roster move to replace Nola in the rotation. His next start would have been on Wednesday against the Miami Marlins, with the next one scheduled for May 1st. With the DL placement being back-dated to April 21st, Nola will be eligible to come off the DL on May 1st, but it's not clear whether he would be able to pitch that day.
The Phillies could go with Ben Lively, who came up for a few days last week while Pat Neshek was on the DL, or they could go with Nick Pivetta. Both are on the 40-man roster. Lively pitched for Lehigh Valley on Saturday, while Pivetta pitched last Thursday, the same day as Nola, giving the edge to Pivetta.
The 24-year old right-hander is 3-0 this season with a 0.95 ERA with the IronPigs. In his three starts, he has thrown 19 innings, giving up 12 hits and two walks, while striking out 24 batters on the season.