As we usher in the official beginning of summer this week, we also usher in the big league debuts of seven players, though only four of them remained on big league rosters by the end of the week’s play on Sunday. Not to fear. All three who were “one and done” starting pitchers are likely to be back sooner rather than later:

DUSTIN ACKLEY
2B, Seattle Mariners
B/T: L/R H/W: 6-1/185 BORN: Feb. 26, 1988
ACQUIRED: Selected in the first round (second overall) of 2009 out of North Carolina
PROMOTED: Contract purchased from Triple-A Tacoma June 16 when IF Luis Rodriguez was sent down.
DEBUT: June 17 in a 4-2 win against the Philadelphia Phillies: The starting second baseman, he batted seventh and went 1-for-4.
NOTES: Likely the most anticipated of this week’s — in fact, this season’s — debut players, the former standout hitter out of North Carolina completed his transition from hard-hitting first baseman to potential outfielder to, for now at least, valuable middle infielder with a big bat. He was hitting .303 with nine homers, 35 RBI and seven steals at Tacoma when recalled to go with 17 doubles in 66 games and a .421 on-base average. In 2010, his lone pro season after signing at the deadline in 2009, he combined between Double-A West Tenn and Tacoma to hit .267 with seven homers, 51 RBI and 10 steals along with 33 doubles. At North Carolina, he batted .412 in three seasons during which the Tar Heels went to the College World Series every summer and following his ’10 debut he moved on to the Arizona Fall League where his .424 average, league-record .581 on-base percentage and .758 slugging percentage earned him league MVP honors. A mature hitter with power potential and plus speed, it’s easy to see why only the presence of a certain Stephen Strasburg kept Ackley from being the first player taken in the 2009 draft.

ANTHONY BASS
RHP, San Diego Padres
B/T: R/R H/W: 6-2/190 BORN: Nov. 1, 1987
ACQUIRED: Selected in the fifth round of 2008 out of Wayne State University
PROMOTED: Contract purchased from Double-A San Antonio June 13 when P Aaron Harang went on the DL
DEBUT: June 13 in a 3-1 win against the Colorado Rockies: The starting pitcher, he earned the win, allowing one run on five hits in five innings, walking four (one intentionally) and striking out one.
NOTES: In a “one and done” debut, Bass joined the club from the Missions rotation, where he’d started the season 7-3 with a 3.41 ERA in 12 starts (including one at Triple-A Tucson), before being dispatched back to the minors to make room for fellow starter Wade LeBlanc the next day. The 2010 California League All-Star had led that league with a 3.13 ERA at Advanced A Lake Elsinore, striking out 112 while walking just 23 in 138 innings. His mid-90s fastball is the best of his repertoire which also includes a slider and changeup.

CHRIS CARPENTER
RHP, Chicago Cubs
B/T: R/R H/W: 6-4/220 BORN: Dec. 26, 1985
ACQUIRED: Selected in the third round of 2007 out of Kent State
PROMOTED: Contract purchased from Triple-A Iowa June 14 when P Casey Coleman was sent down.
DEBUT: June 14 in a 5-4 10-inning loss to the Milwaukee Brewers: the fourth of six pitchers, he threw two-thirds of an inning, striking out one.
NOTES: Carpenter opened the season at Double-A Tennessee before being promoted to Iowa, and had combined between the two stops for a 5.63 ERA in 23 games out of the pen, striking out 26 while walking 21 in 32 innings. That included a 6.41 ERA in 13 games for the I-Cubs. After undergoing Tommy John surgery and another elbow operation early in his college career, he has been healthy since turning pro and brought a 3.29 ERA over three seasons into the 201 campaign, including a 3.16 mark at Tennessee last summer in 23 starts. He moved up the ladder quickly in 2009, pitching at three levels — Class A Peoria (2.44 in 15 starts), Advanced A Daytona (1.44 in five starts) and Tennessee (4.78 ERA in seven starts). With a mid-90s fastball and slider, he continues to refine his stuff and control.

RANDALL DELGADO
RHP, Atlanta Braves
B/T: R/R H/W: 6-3/200 BORN: Feb. 9, 1990
ACQUIRED: Signed as a free agent out of Panama in July 2006
PROMOTED: Recalled from Double-A Mississippi on June 17 when P Tommy Hanson went on the DL
DEBUT: June 17 in a 6-2 loss to the Texas Rangers: The starting pitcher, he took the loss, allowing four runs, three earned, on seven hits in four-plus innings, walking two and striking out two.
NOTES: Another “one and done” starter (one of three on the week), Delgado gave fans a glimpse of why he is so highly regarded in the system despite the numbers on paper. The lanky 21-year-old signed at just 16 but in 2010 he led the Advanced A Carolina League in strikeouts with 120 in just 20 starts at Myrtle Beach before being promoted to Mississippi. His 162 strikeouts in 161 innings last summer led the organization. This year he was 4-4 with a 3.54 ERA in 13 starts for the team, striking out 64 in 73 2/3 innings while walking 26 before his promotion. He throws a fastball in the mid 90s, a curveball and a changeup.

RYAN MATTHEUS
RHP, Washington Nationals
B/T: R/R H/W: 6-3/215 BORN: Nov. 10, 1983
ACQUIRED: Via trade from the Colorado Rockies for P Joe Beimel July 31, 2009
PROMOTED: Contract purchased from Triple-A Syracuse June 10 when P Cole Kimball went on the DL.
DEBUT: June 14 in an 8-6 win against the St. Louis Cardinals: The second of six pitchers, tossed 1 1/3 hitless innings, walking one and striking out two.
NOTES: Originally drafted by the Rockies in the 19th round of 2003, Mattheus opened the 2011 season at Double-A Harrisburg before moving up to Syracuse, posting a 2.45 ERA for the Senators in 13 games and tossing 10 scoreless innings for the Chiefs post-promotion. Between the two stops, he picked up six saves and a 1.46 ERA, striking out 28 in 24 2/3 innings and walking eight, while limiting hitters to a .143 average. Injured for most of the 2010 season during which he threw just 11 innings, he’d been a starter through 2007 with an ERA over 5.00 in each of his three full seasons in that role. His move to the bullpen in 2008 at Double-A Tulsa helped him find his niche as his ERA dipped two full runs and he collected 17 saves with a 3.28 ERA in 2008.

ZACHARY STEWART
RHP, Toronto Blue Jays
B/T: R/R H/W: 6-2/205 BORN: Sept. 28, 1986
ACQUIRED: Via trade from the Cincinnati Reds with 3B Edwin Encarnacion and P Josh Roenicke for 3B Scott Rolen in August 2009.
PROMOTED: Contract purchased from Double-A New Hampshire June 14 when P Kyle Drabek was sent down
DEBUT: June 16 in a 4-3 loss to the Baltimore Orioles: The starting pitcher, he didn’t get a decision but allowed just two runs on seven hits in seven innings, walking one and striking out four.
NOTES: Originally drafted in the third round of 2008 by the Reds out of Texas Tech, few pitchers had a better pro debut that summer than Stewart, who combined for a 1.09 ERA in 24 games of relief between two Class A stops at Dayton and Sarasota. In 2009, the period during which he was traded, he pitched at four stops and combined for a 1.89 ERA in 34 games, 14 of them starts. In 2010 he posted a 3.63 ERA in 26 starts at New Hampshire over 136 1/3 innings and had a 4.39 ERA back there to start 2011 with 49 strikeouts in 69 2/3 innings. He throws a sinking fastball in the mid 90s, a slider and a changeup.

ELIH VILLANUEVA
RHP, Florida Marlins
B/T: R/R H/W: 6-2/235 BORN: July 27, 1986
ACQUIRED: Selected in the 27th round of 2008 out of Florida State
PROMOTED: Contract purchased from Triple-A New Orleans June 15 when IF Ozzie Martinez was sent down.
DEBUT: June 15 in an 8-1 loss to the Philadelphia Phillies: The starting pitcher, he took the loss, allowing all eight runs (earned) on five hits over just three innings, striking out two.
NOTES: The Miami native was, like Bass, a “one and done” callup for that specific start so his struggles did not contribute to that decision. He’d been 4-5 with a 5.23 ERA in 13 starts for the Zephyrs and had allowed a .315 average in 72 1/3 innings, striking out 47, prior to the promotion. But don’t discount Villanueva. In 2010 he was one of the most outstanding pitchers at Double-A, not just in the Marlins organization, with a 14-4 record and 2.26 ERA at Jacksonville, where league hitters managed just a .212 average and he fanned 115 while walking 34 in 179 innings. He has great makeup to go with a fastball which he locates well, a curveball, slider and changeup.