The reigning AL Cy Young Award winner issued four walks while giving up two hits, including a loud three-run home run to Yankees catcher Gary Sanchez.
Snell ended up throwing 39 pitches and just 19 strikes. He got yanked with the bases loaded in favor of left-hander Colin Poche, who allowed every inherited runner to score, saddling Snell with six earned runs.
Following the game, Snell was brutally honest about his performance.
"I've just got to be more aggressive, have more of an attack mindset, and a lot of it is probably with me not being as aggressive in the zone as I should, " he told Eduardo A. Encina of the Tampa Bay Times. "That's my fault. ... It's frustrating. I'll figure it out. I'm confident in that."
It's the third time this season that Snell has allowed six earned runs or more, as he gave up seven against the Kansas City Royals in May and then six against the Detroit Tigers on June 4. Those teams have a combined record of 51-91 in 2019.
The left-hander's shortest start before Wednesday also came against the Yankees, when he lasted just one inning (four earned runs, four hits, four walks) in September 2017.
With his latest dud, the 26-year-old Snell's season ERA jumped from 3.70 to 4.40.