The 22-year-old Canadian took the league by storm last year, scoring eight tries in 20 appearances and being named in the end of season Team of the Year.
Hassler admits he surprised himself with how well he performed and believes he will now be a marked man now opponents have seen what he is capable of.
"I'm not a new guy in the league anymore," he told the South Wales Evening Post.
"Other teams will watch films of me, so I guess it's just about bringing my game to the next level, bringing a couple of things I didn't do last year in and building up.
"Most people would see me as more of a straight runner, but I sometimes throw a sidestep in during training. Hopefully I can get that into my game next year.
"I definitely didn't expect it to go quite as well as it did. I knew coming in, with the injuries the Ospreys had around the wing, that I'd have a good opportunity, but I didn't expect to get thrown into the mix as early as I did.
"I knew if I did get the opportunity I could have a good season, but at the end I was pleased with things on a personal level.
"I didn't even know there was a team of the year until the lads came in and congratulated me, and even then it took a while for me to realise what a good season I'd had individually because I was always thinking about the team."
With Eli Walker, Hanno Dirksen and Aisea Natoga all contesting for a starting spot, Hassler knows he cannot afford to dwell on last season's success if he is to remain Steve Tandy's first choice.
"Everyone's come in from the close season healthy so you could choose from six or seven guys on the wing," added Hassler.
"You've just got to have a good performance and follow it up with a good training week.
"As soon as last season was gone I wiped it clean, I went off with Canada, and I haven't really thought about it until this point.
"I'm just excited to get back in the mix and start to play again.
"I just want to be on the field every week - everyone in this environment wants to do that. That's what we're all pushing for."
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