Ok. So you're gambling on the negative side, he won't even come close to touching his career-best numbers.
It's an upper body injury he's been allowed to heal for a long time. He was ready to come back in round 2.
Gambling on the positive side of things assumes he could pot 25 and 30 playing all season with Drouin and Suzuki. Especially the Suzuki part, with eyes behind his head and both Drouin/Andy having decent speed in the O zone.
Then you're really glad you signed him for 5 years... cause those two straight years of lighting it up next to Suzuki (I don't see Gallagher there, Andy has much more finish) and you'd be ****ed, need to pony up 7+ AAV for another 4-5 years.