The Astros placed Walter on the 15-day injured list Friday, retroactive to July 24, due to left elbow inflammation.

EDGE Analysis

Walter threw seven innings in a start Wednesday, but his arm didn't recover as expected, and he'll require a stint on the injured list. Houston recalled reliever Nick Hernandez from Triple-A Sugar Land in a corresponding move, but it's unclear who will take Walters' spot in the rotation.

Walter did not factor into the decision Wednesday against the Diamondbacks, allowing one run on four hits and a walk over seven innings. He struck out five.

EDGE Analysis

Walter got off to an inauspicious start Wednesday, allowing a home run to Ketel Marte on his first pitch of the game. However, the damage would stop there, as the left-hander held the D-Backs scoreless over his final six innings while allowing just three more hits. While he doesn't have a win since June 27, Walter has delivered three consecutive quality starts, allowing just four runs over 19 innings in that span. His ERA is down to 3.35 with a 0.93 WHIP and a very impressive 52:4 K:BB across nine starts (53.2 innings) this season. Walter is currently in line to face the Nationals at home in his next outing.

Walter (1-3) allowed one run on three hits and a walk while striking out seven over six innings to take the loss Friday versus the Mariners.

EDGE Analysis

Walter put together his fifth quality start, but he was once again done in by a lack of run support. He's now at a 3.66 ERA, 0.96 WHIP and 47:3 K:BB through 46.2 innings over eight starts this season. His strong performance could lead to a tough decision for the Astros' management when the team's rotation is closer to full strength, as Walter has turned some heads during this stint in the majors. He's projected to make his next start at Arizona as Houston operates with a five-man rotation while waiting for some injured pitchers to complete rehab assignments.

Walter (1-2) took the loss Wednesday against the Guardians, giving up two runs on two hits and no walks in six innings. He struck out seven.

EDGE Analysis

Walter continues to provide length for the Astros, having now thrown at least five innings in each of his first seven starts in 2025. The 28-year-old southpaw also tallied 16 whiffs Wednesday, and he's now posted four quality starts for the year. Walter has logged a 3.98 ERA, 1.01 WHIP and a pristine 40:2 K:BB through his first 40.2 frames prior to the All-Star break, and he should continue to hold down a major-league roster spot to help eat innings for Houston's injury-riddled rotation.

Walter did not factor into Thursday's decision against the Rockies, allowing five runs on eight hits while striking out three across five innings. He did not issue a walk.

EDGE Analysis

Walter entered Thursday's game with three quality starts over his last four outings, but he wasn't able to replicate that success in Colorado. He generated 13 whiffs on 91 pitches (62 strikes) but gave up at least one run in three of the five innings he pitched and avoided the loss only thanks to the run support he received from the Astros hitters. Walter is now at a 4.15 ERA, 1.13 WHIP and 36:2 K:BB over 34.2 innings this season, and he's lined up to face the Guardians at home next week.

Walter (1-1) allowed a run on five hits and struck out five without walking a batter over six innings to earn the win over the Cubs on Friday.

EDGE Analysis

Walter limited the damage to a solo home run by Nico Hoerner in the fifth inning. This was his third quality start in five outings this season, and it was a good bounce-back effort after he was tagged for seven runs over six innings by the Angels last Saturday. Walter is now at a 3.34 ERA, 1.04 WHIP and 30:2 K:BB over 29.2 innings. Lance McCullers (foot) will return Saturday, and it's unclear if Walter will stay in the rotation, but he's pitched better than Ryan Gusto if the decision comes down purely to numbers. Walter would be lined up for a road start in Colorado next week if he keeps his place in the rotation.

Walter (0-1) allowed seven runs on nine hits and a walk while striking out six over six innings, taking the loss Saturday versus the Angels.

EDGE Analysis

Walter had been excellent with a pair of quality starts in his last two outings, but he didn't have the same success Saturday. He threw 66 of 99 pitches for strikes, but he gave up a pair of two-run home runs that accounted for a large chunk of the damage on his line. Even with the poor outing, Walter has a 3.80 ERA, 1.10 WHIP and 25:2 K:BB over 23.2 innings through four starts. The 28-year-old showed impressive control with a 49:7 K:BB over 47.2 innings with Triple-A Sugar Land after missing all of 2024 due to a shoulder injury. Walter is tentatively projected for a tough home start versus the Cubs in his next outing, and his place in the rotation is likely safe for as long as both of Lance McCullers (foot) and Spencer Arrighetti (thumb) are on the injured list.

Walter didn't factor into the decision Sunday against the Twins, allowing one run on six hits and no walks with nine strikeouts over 6.2 innings.

EDGE Analysis

Walter is temporarily serving as the sixth man in a six-person rotation for the short-handed Astros, but the 28-year-old has performed more like an ace in limited action this season. Sunday's outing was his third MLB start of the campaign, and his second time allowing no runs. His nine strikeouts marked a career high and bumped his K:BB to 19:1 across 17.2 innings. While he likely won't retain a spot in the big-league rotation once the Astros get healthier, he could stick around for one or two more trips through the rotation. He'd be in line to start during a three-game set against the Angels next weekend.

Walter is slated to start Sunday's game against the Twins in Houston, Brian McTaggart of MLB.com reports.

EDGE Analysis

As expected, Walter will receive a second straight turn through Houston's six-man rotation while the Astros remain short on healthy arms with six starting pitchers currently residing on the injured list. Only one of those six injured pitchers (J.P. France) has resumed facing hitters at this point, so Walter could be in store for an extended run in the rotation. He's pitched well in both of his two starts with Houston this season, striking out five over five shutout innings May 20 at Tampa Bay and recording another five strikeouts over six innings of two-run ball this past Sunday in Cleveland. The 28-year-old southpaw has enjoyed a similar level of success at Triple-A Sugar Land, where he compiled a 2.08 ERA, 0.76 WHIP and 49:7 K:BB in 47.2 innings prior to getting called up last week.

Walter allowed two runs on six hits while striking out five across six innings, but he did not factor into Sunday's decision against the Guardians. He did not issue a walk.

EDGE Analysis

Walter was promoted from Triple-A Sugar Land to make his second major-league start of the season. He put the Astros behind after yielding a two-run homer to Bo Naylor in the second, but Walter kept the Guardians off the board the rest of the way and retired the last 10 batters he faced. Per Matt Kawahara of the Houston Chronicle, the Astros plan on using a six-man rotation during their stretch of 13 straight games, which puts Walter in line to make his next start against the Twins at home next weekend.