Parker surrendered eight runs -- seven earned -- on six hits, three walks and two hit batsman over 3 2/3 innings pitched. He did fan five in the brief outing, and five of the runs he gave up came with two outs in the fourth. His Mobile team fell, 10-4, to the Carolina Mudcats.
The 22-year-old righty is roundly considered the top prospect in the Arizona Diamondbacks system, and 2011 is a crucial year in his development.
In a July 2009 outing for the BayBears, Parker complained of elbow tightness. He was shut down for the rest of the season and underwent Tommy John surgery that October, which caused him to miss all of the 2010 season. He made four appearances with the big league club in Spring Training, giving up four runs over 6 1/3 innings.
Parker started Monday's regular-season debut by issuing a leadoff walk and surrendering a single and then a run on a sacrifice fly before striking out Carolina's Denis Phipps. He appeared to settle down after getting the punchout, retiring the next hitter on a grounder.
He faced the minimum in the second and struck out two during a scoreless third.
The fourth inning, though, brought trouble. Phipps, batting first in the frame, ripped a 2-1 pitch into left field for a double, and Parker walked Cody Puckett after picking up his fifth strikeout.
Parker, facing Jose Castro, then balked to send the runners to second and third. He gave up a double to Castro, then got Chris McMurray to fly out to center before hitting two consecutive Carolina batters.
The next hitter, Mike Costanzo, was down in the count, 1-2, when he pulled Parker's pitch over the right-field wall for a grand slam. Parker was then relieved by Kyler Newby.
Costanzo homered again in the sixth inning and tallied six RBIs.
D-backs prospect Paul Goldschmidt, who had homered four times in the first four games of 2011, had an RBI base hit in the third and legged out a ground ball to third base for a single in the fifth.