''In a lot of ways, it might be one of his best outings this year,'' Showalter said.
Nelson Cruz hit two of Baltimore's season-high four home runs, Chris Davis and Matt Wieters also connected and the Orioles beat the Toronto Blue Jays 10-8 Wednesday night.
Tillman allowed nine hits, seven runs and three homers, but impressed his manager by going back out after a six-run, 11 batter second inning and working into the sixth.
''That's what you ask of your starters, is that even if you don't have your best stuff to be able to go deep in the game,'' Wieters said. ''Most starters would have shut it down after the second inning. He was able to get into the sixth, which speaks to what type of competitor he is.''
Showalter said he came ''real close'' to taking Tillman out after the second, but decided to stick with him a little longer. Tillman repaid that faith by retiring 10 of the next 11 batters, striking out five.
''I told (pitching coach Dave Wallace) `Let's see the first couple of hitters and see how it goes,''' Showalter said. ''He came out with a little more stuff and gave us some needed innings.''
Tillman (3-1) won for the third time in four starts despite allowing two more earned runs than he'd given up in his four previous outings this season combined. Tillman, who walked two and struck out a season-high seven in 5 2/3 innings, said he overcame his second-inning struggles by throwing more off-speed pitches.
''My fastball wasn't cutting it, I wasn't able to command it,'' he said. ''When I'm not able to command it, I have to go to plan B.''
Cruz hit a solo homer off Dustin McGowan in the third and a grand slam off Todd Redmond (0-2) in the fifth, giving him six homers this season and 11 career multihomer games. The slam was his seventh.
''Nelson is a great hitter,'' Wieters said. ''I always had trouble calling pitches against him so I'm glad he's on our team. He's a huge addition to the middle of our lineup.''
Davis hit a solo homer in the first, and Wieters added a solo drive off J.A. Happ in the seventh.
Shortstop J.J. Hardy (right hamstring) and Wieters (right forearm) both returned to Baltimore's lineup after sitting out two games. Wieters hit a two-run double in Baltimore's six-run fifth and Hardy added a sacrifice fly.
Brett Lawrie hit a three-run homer for Toronto, his second home run in two games. Jose Reyes had a two-run shot and Ryan Goins hit a solo homer, his first this season.
Ryan Webb got one out in the sixth, Brian Matusz allowed one run in two-thirds of an inning, and Darren O'Day struck out Jose Reyes to strand runners at first and second in the seventh.
Tommy Hunter gave up three singles in the ninth as Toronto loaded the bases with one out, but Jonathan Diaz grounded into a game-ending double play to give Hunter his sixth save in seven chances.
Cruz, who leads Baltimore with 21 RBI, has driven in at least one run in six consecutive games, the longest streak by an Orioles player since Davis did it from Sept. 26 to Oct. 2, 2012.
''We all know what he's capable of,'' Showalter said of Cruz.
Doug DeCinces holds the Baltimore record, driving in at least one run in 11 straight games in a streak that started in September 1978 and ended the following April.
Davis' homer was his 18th against Toronto since the start of the 2012 season, the most by any opponent. Teammate Adam Jones is second with 14.
Blue Jays right-hander Dustin McGowan allowed six runs and five hits in four-plus innings, and said he started to tire in the fifth.
''At 60 pitches I kind of seem to be falling backwards a little bit,'' McGowan said. ''I feel good, my arm feels great. It's just sometimes it seems like the ball is not coming out quite right after 60-65 pitches.''
Toronto OF Jose Bautista drew two walks, increasing his major league-leading total to 27. Bautista has reached safely in all 21 games this season, the longest active streak in the majors. ... Baltimore 3B Manny Machado (left knee) had three hits in his final game at extended spring training. Showalter said Machado will begin a minor league injury rehabilitation assignment Friday at Class A Frederick. ... Baltimore RH Bud Norris (0-1) faces Toronto's Drew Hutchison (1-1) in Thursday's series finale.