Frawley was bench-pressing his usual weight load when he suddenly felt a sharp pain and " a popping sensation".
The diagnosis was a torn pectoral and 10-12 weeks on the sidelines.
After fully healing and returning to the Melbourne side, Frawley says the injury had a big effect on his confidence.
"It was very disappointing, especially for the injury to happen in the weights room," Frawley told melbournefc.com.au.
"I was just doing my normal weights session and I got to the fourth rep and it just popped. I popped my shoulder out and my pec went. It was a bit weird.
"We weren't even training on the park with the boys. It was very frustrating and quite a setback mentally. You wonder if you can get back to what you were as quickly as possible.
"Once you get out there playing, it feels normal again. Now I'm back out there I'm fine."
Frawley made his return in the round-two loss to Hawthorn. Without setting the world on fire, he had the legs to go the distance but admitted some concern about his upper body strength.
"I started running two weeks after I did the injury so that wasn't the big issue. I just wanted to be able to keep up on the physical side of the game, pushing off opponents and that sort of stuff," he said.
"That was going to be the thing that would hold me back. I had a lot of running under my belt."
Pectoral injuries aren't among the most common in the AFL, but Frawley did have some basis for comparison with one of Melbourne's assistant coaches who he consulted throughout his recovery.
"Todd Viney did both of his one pre-season. He is back at the club now and I got a bit of advice off him and went through the pros and cons of getting surgery," he said.
"I decided to get surgery because if I didn't it would be permanently damaged and I'd have half my strength on that side. After surgery you pretty much gain all your strength so I decided on that option and came out pretty well."
Frawley's full recovery was vital to a Melbourne side looking to rise up the ladder last year. After coming second in the club's best and fairest last season and earning All Australian selection, he is now rightfully considered one of the club's most valuable players.
His stocks may have risen in the past 12 months but Frawley says he is still coming to terms with the idea of him being one of Melbourne's senior players.
"We've got leaders at the club and I try to help them out, but I've been there five years. We've got a young group and I try to lead a bit, but it's up to you individually if you want to step up," he said.
"Col Garland has really stepped up in that area. Mark Jamar had a good year last year. You feel a little bit of pressure but you just try and work together and lead on the field."
