I think it's important to look at this statistically, since this is a results business.
I feel like it's worth comparing to the Bruce Cassidy interim situation. In 2017, under Claude, they had the 20th best PT% in the league (0.527), 22nd in GF/GP, and 13th in GA/GP, with a -6 goal differential over 55 games. Under Cassidy, they had 6th best PT% in the league during his 27 games coached (0.685), 1st in GF/GP, 4th in GA/GP, and +29 goal differential. That's a clear case of massive improvement. In terms of an 82-game pace, we're talking about a 26 point improvement.
Let's compare that to Monty versus Sacco this year. With Monty they were 20th in PT% (0.475), 31st in GF/GP, 28th in GA/GP, with a -21 goal differential over 20 games. With Sacco, they've only been 23rd in PT%, but improved to 0.522, 21st in GF/GP, 18th in GA/GP, with a -6 goal differential over 45 games. That would be an improvement of 8 points on an 82-game pace. Yes, there have been injuries and promotions/demotions, but it's largely been the same group, besides H. Lindholm.
Throwing some other numbers out there, at all strengths, under Monty, they were 31st in GF% (41.03) vs. 9th in xGF% (52.33), while under Sacco, they've been 19th in GF% (48.85) vs. 19th in xGF% (49.84). We can argue whether that's a situation of luck, or whether you'd prefer the higher xGF% situation or having a smaller difference in GF% vs. xGF%.
Yes, there's been improvement, but it's not like that improvement has been anything to get excited over. I don't think we can say Sacco has coached them to perform above their talent level and that's what you look for in a coach. I also have a tough time saying "let's give him a training camp", when we're talking about a guy who's been here since Claude. This was a trade deadline of organizational change, keeping a guy like Sacco at the helm, who's been here 10+ years, would just be a sign of business as usual.