An actual NHL warm body would be enough of an upgrade.
The Flames are desperate for about 40 more goals from their forwards on top of the remarkable season the top line had.
The halfway mark last year was 243 goals. Calgary scored 216. The last time the flames scored more than 243 goals was 2008/2009. The Flames had 2x35+ goal scorers/80+ points and 5x20+ scorers that season. This season they had 1 guy score 31 and only 4 guys score 20. At the halfway point in the season the Flames were 21st in Goals for, so it wasn't just losing players to injury at season's end and it wasn't just coaching.
If the Flames want to be serious contenders, or even serious about holding a playoff spot they're going to have to score in the 240-250 goal range and keep their goals against about where they are now or better.
At this point the team building is honestly pretty simple for Calgary. There's no way to coach yourself to another 40 goals, you can really only coach yourself to less goals against. If they want to score they'll have to add it by free agency, trade or miracle season from Dube/Bennett/Janko. A 60 goal season from Monahan might do it but I wouldn't bet the farm on that happening.
So, to answer your question, yes, Hayes is enough of an upgrade to make a dent in that goal deficit, he probably cuts into it by half meaning the roster needs another middle six scoring winger to get the rest of the way there. You can probably find that guy in free agency, but you'll probably want two of those guys to make sure you make the dance and one of them doesn't pull a brouwer/versteeg/jagr.
Tre has already gone all in with the draft picks in the last 2 or 3 years. The Flames went all in this year and decided to 'check' at the deadline. Bite the bullet, give Peters something to work with, something to have immediate success with and let the GM that succeeds you deal with the fallout of dealing all your picks away for 3 or 4 years and the albatross cap hits it will take to bring in enough scoring.
10th Place in GF:
- 2018: Colorado, 255
- 2017: Islanders, 239
- 2016: Calgary, 229
- 2015: Detroit, 231
- 2014: Dallas, 231
Even in the lower scoring years before the recent stick infraction crackdown, the Flames are basically another Jankowski away from where they need to be.
The difference was a Jake DeBrusk or a McAvoy or Heinan. Maybe Phillips turns out to be Calgary's Yanni Gourde, but they'd still need another 15 goal winger to be comfortably in the mix.
If the Flames want to do anything in their window now, they're going to have to move more picks and assets to bring in NHL calibre players onto the roster immediately. Overpay if need be, but get some scoring onto the roster before Gaudreau is 27 years old and has only a year left on his deal.
Give players a reason to want to come and or stay in Calgary other than an invitation to play stifling defensive hockey for 78 games before you know if you're going to make the playoffs or not.
Give the Fans something to actually cheer for. At this point, who cares what it costs in terms of assets, it's better than not having draft picks and also not having playoffs.