Now, Appel, ranked No. 46 on MLBPipeline.com's Top 100 Prospects list, will look to put his struggles at Lancaster behind him when he makes his first start for Corpus Christi on Wednesday, facing San Antonio. Fans can watch the game, which begins at 8:10 p.m. ET, on MiLB.TV.
In addition to his appendectomy this winter, Appel also dealt with wrist and thumb injuries this season. The Astros' No. 2 prospect wasn't helped by his home park in Lancaster, which is known as one of the most hitter friendly venues in baseball. In seven home starts, Appel went 1-4 with a 13.70 ERA. On the road, he was 1-1 with a 5.48 ERA.
In Corpus Christi, Appel joins outfielder Delino DeShields and second baseman Tony Kemp, the Astros' Nos. 11 and 17 prospects. DeShields is hitting .241/.347/.349 with 43 stolen bases in 84 games this season. Kemp, the Astros' fifth round pick last year, began the season with Appel in Lancaster. He was promoted last month and is hitting .308/.393/.485 in 32 games with the Hooks.
Appel will face a tough test in his first start with Corpus Christi. San Antonio is led by catcher Austin Hedges and outfielder Hunter Renfroe, the Padres' Nos. 1 and 4 prospects. Hedges, ranked No. 26 on the Top 100, has struggled at the plate this season and enters Wednesday hitting .236/.279/.356 with six home runs in 92 games.
Renfroe, No. 78 on the Top 100, was selected 12 picks after Appel in last year's Draft. Like Appel, he began the season in the California League and was promoted to San Antonio after hitting .295/.370/.565 with 16 home runs in 69 games at Class A Advanced Lake Elsinore. In 29 games since joining the Missions for the second half of the season, Renfroe is hitting .241/.303/.407 with four home runs.
In addition to Appel, a few other pitchers ranked on the Top 100 are scheduled to start Wednesday, including Archie Bradley (No. 12), Nick Kingham (No. 66) and Alex Gonzalez (No. 100). Fans can watch Kingham and Gonzalez on MiLB.TV, beginning with Kingham and Triple-A Indianapolis facing Buffalo at 7:05 p.m. ET Gonzalez and Double-A Frisco will host Midland an hour later.
Also among pitchers scheduled to throw Wednesday is White Sox No. 1 prospect Carlos Rodon, the third overall pick in this year's Draft. Rodon made his professional debut last week in the Arizona League and will now join Class A Advanced Winston-Salem. Like they did with Chris Sale in 2010, the White Sox are keeping Rodon in the bullpen this season to ease his transition and he is slated to make a relief appearance for the Dash on Wednesday when they face Frederick.
Top prospect probables
Tyler Anderson (Rockies' No. 12), Tulsa vs. Springfield
Mark Appel (Astros' No. 2), Corpus Christi vs. San Antonio
Tim Berry (Orioles' No. 7), Bowie at Akron
Archie Bradley (D-backs' No. 1), Mobile vs. Jackson
Austin Brice (Marlins' No. 19), Jupiter at Brevard County
Mike Clevengier (Angels' No. 10), Inland Empire at Stockton
Jonathon Crawford (Tigers' No. 4), West Michigan vs. Lake County
Brian Flynn (Marlins' No. 11), New Orleans vs. Iowa
Domingo German (Marlins' No. 12), Greensboro vs. Asheville
Alex Gonzalez (Rangers' No. 5), Frisco vs. Midland
Tyrell Jenkins (Cardinals' No. 16), Palm Beach vs. Lakeland
Brian Johnson (Red Sox's No. 11), Portland vs. Reading
Taylor Jungmann (Brewers' No. 12), Nashville at Colorado Springs
Nick Kingham (Pirates' No. 5), Indianapolis at Buffalo
Jairo Labourt (Blue Jays' No. 16), Vancouver at Boise
Michael Lorenzen (Reds' No. 4), Pensacola at Mississippi
Trevor May (Twins' No. 8), Rochester vs. Lehigh Valley
Zach Petrick (Cardinals' No. 17), Memphis at Omaha
Tyler Pike (Mariners' No. 15), Jackson at Mobile
Robbie Ray (Tigers' No. 2), Toledo vs. Norfolk
Matthew Smoral (Blue Jays' No. 20), Bluefield at Johnson City
Jen-Ho Tseng (Cubs' No. 15), Kane County at Wisconsin
Nick Travieso (Reds' No. 9), Dayton at Lansing
Logan Verrett (Mets' No. 20), Las Vegas vs. El Paso
Mike Wright (Orioles' No. 8), Norfolk at Toledo