Technically, the injuries to starting pitchers started much earlier this season, when Charlie Morton went on the DL with a season-ending injury. There were other smaller injuries, like Vincent Velasquez going on the DL, but for the most part, everything was okay with the starters until recently.
Aaron Nola (right elbow strain) and Zach Eflin (bilateral patellar tendinitis) wound up on the DL and it's possible that neither will return this season. Until Nola would be ready to pitch again, he would need time to get back to full strength and there would be precious little time left in the season for him to pitch. It's likely the Phillies won't push him and will instead just cut his season short.
Eflin could be in much the same position. If he were a veteran pitcher on a team in contention for the postseason, he might be under pressure to rush back. In the Phillies scheme of things, there's no need to rush.
On Wednesday, Jeremy Hellickson worked his way through five innings, but when he left the field after the fifth, he was holding his back. The injury was described as back tightness, which is too vague and general to gauge just how serious the injury might be. His inclusion on the DL though, would make things very interesting, since the Phillies would then be down two starters, who haven't yet been replaced with reinforcements from the minors.
With off-days, the Phillies could limp through most of the month of August with four starters. That, however, would go against their stated plan of limiting innings for young pitchers late in the season, so it's likely that they fill both spots.
In terms of who would fill the two spots, the answers are pretty easy. Adam Morgan and David Buchanan have both pitched very well lately for Lehigh Valley and both were likely to come back to the majors in September anyway, so their timetable may just be accelerated. Obviously, the concern is with the major league team and getting them through the rest of the season, but the injuries to Phillies pitchers are going to hurt at the minor league level.
The Lehigh Valley IronPigs, who haven't been in the postseason since 2011, currently have a 5 1/2 game lead in the wild card standings of the International League, but are still hoping to make up the three games separating them and the Scranton/Wilkes-Barre RailRiders, the Triple-A affiliate of the New York Yankees. Since the minor league all-star break about a month ago, the Phillies have lost Edward Mujica (opted out of his contract), Luis Garcia (recalled), Michael Mariot (recalled), Edubray Ramos (recalled) and Jake Thompson (recalled). Now, Buchanan and Morgan, are also likely to exit. That doesn't bode well for their postseason hopes, and if they do make the playoffs, it could be a tough fight.
At Reading, nobody doubts that the Reading Fightin Phils, the team with the best record in all of baseball, will make the playoffs. Obviously though, if Buchanan and Morgan head down the Pennsylvania Turnpike for Philadelphia, others are likely to make the trip up Route 222 from Reading to Lehigh Valley.
Nick Pivetta (11-6, 3.41) is the likely first choice. After that, there could be some discussions. Mark Leiter (5-1, 3.42) has had a good season, and right-handers Ricardo Pinto (4-4, 4.18) and Tyler Viza (4-3, 4.34) could also be considered. Tom Eshelman has pitched well lately, even though his overall 5.01 ERA is messy, at best. Viza and Eshelman both opened the season at Clearwater.
As the ripples reach further into the minors, Clearwater and Lakewood would be affected. John Richy (4-4, 3.53) and Shane Watson (4-4, 4.01) are names to watch at Clearwater, while Lakewood has pitchers like Harold Arauz (3-5, 3.89), Tyler Gilbert (6-7, 3.48) and Franklyn Kilome (4-8, 4.14).
After that, the Phillies would have to consider which of their very young pitchers to move up from Williamsport and the Gulf Coast League.
Keep in mind, that these moves only take the pitching moves into consideration. Names like J.P. Crawford, Nick Williams, Andrew Knapp, Jorge Alfaro and Roman Quinn have all been talked about as additions to the Phillies roster when teams can take their rosters up to the 40-man limit.