That's a definite over payment.
Panarin definitely left money on the table - his cap hit would have been considerably higher if he had accepted CBJs offer, so this is far from an overpayment from this perspective. comparing him to Matthews is also nonsense, since you're buying 100% UFA years with Panarin. big UFAs cost money, they will cost more money every year, and it's WAY better to spend this money on first line talent in it's prime than on 2 aging veterans you could get for the same money.
the Rangers cap situation may look concerning, but it's not as bad as it looks like - this year is the only year in which the Girardi buyout costs 3,6M instead of 1,1M. Smith and Beleskey will probably be buried in the AHL and Namestnikov is getting traded imo - his contract is not an anchor and he is still a useful player, but it's hard to justify the cap hit. he's good enough to be tradeable with a return rather than a sweetener. Staal and Lundqvist will come off the books before the young players stepping up will require big deals themselves.
this season, the Rangers might not be contenders yet. when everyone grows into their supposed role on the team, this team looks DANGEROUS. give it one or two years - until then, I hope there won't be immediate panic among the fans if it doesn't pan out as they might expect due to the hype of the past weeks.