It’s a good deal for KC but let’s not underrate Smith too much here. Reality is for 22 or so million a year, that’s about his worth.
KC only make this deal because they have Mahomes. Even then there is risk here. Smith is an established starting Qb which is most certainly in the top 10 or 15 at worst in the league. Is he franchise? Can he carry his team to the SB? The answer to both those Qs is probably no. But he’s functional and with the correct support cast is very much capable of QBing a team to a SB title as a functional QB. We don’t know what Mahomes is yet, let alone what he will become. Upside? Sure. But plenty of upside QBs have bombed out.
Smith is, IMO, no different to Cousins. Who is about to get a huge payday, likely more than Smith, so in that sense there is rationalle to this deal for Washington. Neither capable of lifting a team themselves.
In the end it’s a sensible deal for both teams I think. Redskins pay less than they’d have to for a similar level QB. KC get to play their young QB who they feel has better potential, and at a much lower cost than retaining Smith.