Stewart started the scoring for Double-A Erie on Friday night with a first-inning grand slam. It was the second homer in three games for the 23-year-old slugger, who paces the Eastern League with 12 home runs and 32 RBIs. In 2016, Stewart's first full season, he finished fifth in the Minor Leagues with 30 home runs.
Clarke, 24, has completed six innings in four straight starts for Double-A Jackson, during which he's gone 3-0 with a 1.50 ERA and a .214 opponents' batting average in 24 innings. He's 4-1 in eight starts overall with a 2.25 ERA and 37 strikeouts in 40 total innings.
Castillo has permitted more than two earned runs just once in eight starts for Double-A Pensacola. The hard-throwing 24-year-old righty owns a 3.07 ERA in that span, with a 37-to-7 strikeout-to-walk ratio in 44 innings.
Long, the Angels' third-round Draft pick in 2015, fanned a season-high eight batters in his latest start for Mobile. He gave up two earned runs in five innings -- his third straight outing with that result -- with six hits allowed and one walk. The 6-foot-5 righty owns a 3.12 ERA in 26 innings (five starts) since being promoted to the Southern League.
Saturday's Top 100 prospect probables
No. 17 Francis Martes (Astros' No. 1) vs. Marco Gonzales (Cardinals' No. 19), Fresno vs. Memphis (10:05 p.m. ET on MiLB.TV)
No. 37 Braxton Garrett (Marlins' No. 1), Greensboro vs. Delmarva (7 p.m. ET)
No. 77 Grant Holmes (A's No. 3), Midland vs. San Antonio (8 p.m. ET on MiLB.TV)
More top prospect probables
Andrew Moore (Mariners' No. 4), Tacoma at Iowa (Triple-A) Jake Junis (Royals' No. 5) vs. Frank Duncan (D-backs' No. 24), Omaha vs. Reno (Triple-A) Jacob Faria (Rays' No. 9), Durham vs. Gwinnett (Triple-A) Brian Johnson (Red Sox's No. 11), Pawtucket at Buffalo (Triple-A)
Tyler Eppler (Pirates' No. 24), Indianapolis vs. Toledo (Triple-A)
Ariel Jurado (Rangers' No. 3), Frisco vs. Corpus Christi (Double-A)
Brandon Waddell (Pirates' No. 16) vs. Artie Lewicki (Tigers' No. 21), Altoona vs. Erie (Double-A) Miguel Almonte (Royals' No. 16), NW Arkansas at Springfield (Double-A) Drew Anderson (Phillies' No. 21), Reading vs. New Hampshire (Double-A)
Parker French (Rockies' No. 22), Hartford vs. Akron (Double-A)
Jordan Guerrero (White Sox No. 30), Birmingham vs. Tennessee (Double-A)
Scott Blewett (Royals' No. 4) vs. Brian Gonzalez (Orioles' No. 19), Wilmington at Frederick (Class A Advanced)
Peter Lambert (Rockies' No. 8), Lancaster at Inland Empire (Class A Advanced)
Mitchell White (Dodgers' No. 10) vs. Justin Donatella (D-backs' No. 26), Rancho Cucamonga vs. Visalia (Class A Advanced) Sandy Baez (Tigers' No. 10) vs. Edgar Garcia (Phillies' No. 26), Lakeland at Clearwater (Class A Advanced)
Vladimir Gutierrez (Reds' No. 11), Daytona at Tampa (Class A Advanced)
Connor Jones (Cardinals' No. 22), Palm Beach vs. Florida (Class A Advanced)
Joan Baez (Nationals' No. 22), Potomac at Lynchburg (Class A Advanced)
Jordan Romano (Blue Jays' No. 23), Dunedin at St. Lucie (Class A Advanced)
Joey Wentz (Braves' No. 13), Rome vs. Lexington (Class A)
Aaron Civale (Indians' No. 21) vs. Gregory Soto (Tigers' No. 29), Lake County vs. West Michigan (Class A)
Darwinzon Hernandez (Red Sox's No. 25), Greenville vs. Asheville (Class A)
Mike Rosenbaum is a reporter for MLB.com. Follow him on Twitter at @GoldenSombrero. This story was not subject to the approval of Major League Baseball or its clubs.