He emerged from the five-plus inning performance feeling satisfied, but knows he isn't ready to join the Yankees.
"All in all, it was a positive evening," said the 39-year-old Pettitte, who allowed four runs (three earned), recorded three strikeouts and walked one. He threw 81 pitches, 59 for strikes and took the loss in a game won, 10-4, by Erie. "I know I'm not there yet.
"I wasn't happy with my command. I made a few more mistakes than I had in my other starts. The weather was obviously different than it was in Florida, which is something I have to get used to, as well."
Pettitte, whose fastball was clocked at 87-88 mph, surrendered runs in the first, fourth and fifth frames. He said he left "a few too many pitches in the zone," which led to a few hard-hit balls by the Erie Seawolves.
"A couple of those kids got some good swings against me," said Pettitte.
Yankees general manager Brian Cashman, who watched Pettitte's first cool-weather start (temperatures were in the mid-50s), also agreed the effort was "a step forward," but stated the pitcher isn't ready to face Major League hitters.
"Andy is between a quarter and halfway through Spring Training after being off for 16 months," said Cashman. "He got to near 85 pitches in this start. He looks good and feels good. He's healthy. His strength and stamina have to get to the right levels."
Cashman also reiterated a few times the right labrum injury to Michael Pineda adds no urgency to Pettitte's situation.
"Today was a devastating day for us on the big league level, but in no way does it affect Andy's situation," said Cashman. "He has to go through the steps. In his next start, we'll aim for 100 pitches. When everything is right -- strength, stamina and pitches -- he'll be ready. He's not [there] yet, and Michael's situation doesn't change that.
"If I lost every starter in the Yankees rotation, I still wouldn't slot Andy in there."
Pettitte's main goal in this start was to throw 80-85 pitches, and he achieved that. Having thrown 78 through five innings, he pitched to Erie's Rob Brantly in the top of the sixth before his evening concluded.
That was a major step up from his last start in extended spring training in Florida.
"I knew I had 78 pitches after five innings, and I wanted to push it," Pettitte said. "I threw 66 in my last start and I was tired. I was tired tonight, but I wanted to get over 80.
"That, the weather, pitching out of trouble [in the first, fourth and fifth innings] are all things my body has to get used to again. My strength is also not quite there yet. I need to be able to 'pop' one in there when I'm at 80 pitches, and I wasn't able to do that yet."
Pettitte, who has been following the Yankees' progress, and has watched as many games as he's been able to, is experiencing the ups and downs of his comeback.
"I can't wait to get to the Yankees and do battle with those guys," Pettitte said. "But it won't do either myself or the team any good until I'm ready, and I'm not.
"I thought the weather affected my velocity. I thought my velocity was better in Florida, but that's all part of this grind of coming back. I know I'll get there."
Cashman talked of at least two, or possibly three Minor League starts. Pettitte will remain with the Thunder, but he's not sure where his next start will be. Neither does Cashman.
"After each start, we take a step back," said Cashman. "We take a look at schedules, level of completion, weather, all those factors. Then, we will slot him. We do like to have our players in this situation perform with our affiliates, on our mounds and in the stadiums we know.
"We'll decide where Andy pitches next in a few days."
Pettitte, who has made 479 regular-season starts and amassed a 240-130 mark over his 16-year career with the Yankees and Houston Astros, knows his body well and what level he has to perform at to help the Yankees. The mentioned goal of a mid-May return to the Bronx appears realistic, but he is still a work in progress.
Jed Weisberger is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.