Romero entered the day with seven innings of one-run ball this spring despite five walks, thanks in part to six strikeouts.
"I think it was just a matter of not throwing strikes. I think that I just got in trouble with that, falling behind in counts," Romero said. "It was a battle. I've just got to keep moving forward."
Three of the eight outs Romero recorded came on the basepaths, including a pair of runners caught off second for both of his outs in his third and final inning. Three of his seven balls put in play went for base hits, including Austin Jackson's two-run homer in the second inning.
Despite drawing four consecutive walks in the third inning, Detroit scored its lone run that frame when Hernan Perez -- who'd hit a leadoff triple -- bolted home on a pitch in the dirt. Reliever Jeremy Jeffress prevented further damage to Romero by striking out Avila but then gave up three walks himself in the fourth.
The bulk of the damage in the fifth inning came off promising Jays prospect Marcus Stroman, who retired one of the eight batters he faced. Three straight singles following Kinsler's leadoff walk plated one run and loaded the bases for Kelly, who jumped on a full-count fastball and sent it deep to right-center for his second homer of the spring.
Kinsler came back up later in the fifth and turned on a Marcus Walden offering, sending it to the left-field berm to score Ben Guez and Torii Hunter.
Guez, who crossed the street from Minor League camp for a rare start with Rajai Davis scratched as a precaution for his sore right hamstring, went 3-for-3 with three walks. Jackson went 2-for-5 with three runs scored, raising his batting average for the spring to .459.
The support was plenty for Tigers starter Drew Smyly, who gave up two hits and a walk along his way to five scoreless innings, with three strikeouts, against a lineup that featured Jose Bautista, Jose Reyes, Edwin Encarnacion, Brett Lawrie and Melky Cabrera.
Up next: The Tigers have their lone off-day of the spring on Wednesday, but Rick Porcello has a day of work on the back fields at Tigertown. He's scheduled to pitch in a Minor League game to stay on turn for his first start of the spring. The full squad returns to action at 1:05 p.m. ET on Thursday, when Max Scherzer makes his next-to-last start of the spring against the Nationals at Space Coast Stadium in Viera, Fla. Kinsler, Avila and Jackson are among the Tigers scheduled for the lineup.