PORTLAND – Michael Bowden was far from disconsolate after his second start of the season for the Portland Sea Dogs Friday night. Yet the 21-year-old righthander wasn’t pulling a lot of punches when asked to assess his performance, either.

“I haven’t gone five innings yet, and that’s a disappointment not only to myself, but I’m letting my team down as well,” Bowden said.

The Boston Red Sox No. 3 pitching prospect (ranked seventh in the organization overall by Baseball America) is typically even more frank with himself. Sea Dogs manager Arnie Beyeler described Bowden (pronounced like Bowdoin) as a perfectionist.

“He’s a tireless worker and very hard on himself,” Beyeler said. “He’s one of those guys you never really know is around. He takes care of his business all the time.”

As a youngster, Bowden had to learn how to take care of business on the mound pretty much on his own, which may explain why he’s seldom satisfied and, as Sea Dogs catcher John Otness said, is a “maniac work guy.”

Bowden grew up poor outside of Chicago. As a result, he received no extra instruction on pitching. He didn’t have a pitching coach at Waubonise Valley High School, either, so his unorthodox over-the-top pitching motion, with the hitch in the back, was entirely self-taught.

Bowden was chosen 47th overall by the Red Sox in the 2005 draft with the pick they received as compensation for losing Derek Lowe as a free agent. He finally got the professional instruction he had been craving the following year, his first full season as a professional, when he met his first pitching coach, the former Sea Dogs pitching coach Bob Kipper, at Single-A Greenville (S.C.). Both being Illinois natives, they bonded immediately.

“He knew me better than I knew myself,” Bowden said. “He taught me a lot about what it takes to be a pitcher and to be a man.”

Under Kipper’s tutelage, he excelled at Greenville (9-6, 118 Ks in 107 innings). It carried over when he got promoted to Lancaster (California) to start last season.

The promotion to Portland came on May 14. Bowden shined in his first three starts, then struggled in the second half of the season, finishing 8-6 with a 4.28 ERA in 19 starts. “Last year, a lot of things didn’t go my way. I didn’t really trust my stuff. I wasn’t very confident and that carried over into my performance,” he said.

Bowden was too hard on himself at times last year, according to Portland pitching coach Mike Cather.

“I chalk it up to the fact that he probably never failed before,” Cather said. “He was so dominant. You have to be tested. There will be a time in your baseball career where you’re tested, whether it be Double-A, Triple-A or the big leagues, where they’re going to get your number. How you react to that tells you a lot about how you’re going to perform as a professional baseball player.”

“He’s very intense in everything that he does,” he added, “and he’s actually much more mature with it this year.”

The outlet for that intensity remains Bowden’s work ethic, which has drawn raves from his coaches and teammates.

“He takes that preparation and applies it to everything,” Otness said. “He takes that into his bullpens, he does it in his games. It just carries all the way through.”

It could carry him through to the big leagues, in addition to a low-to-mid-90s fastball and the best control among Boston’s minor leaguers (77 walks in 261 career innings).

“I know what I need to do to be successful at the Double-A level.

“It’s all a learning experience,” Bowden said. “I can go out there and have some bad outings. You’ve just got to reflect on them, learn from them and try to get better every day.”