Chychrun has his flaws and some of the analytics show that for sure. He's not #1D because of those flaws, IMO. Atleast not yet.
That said. Goals and generally a threat from the blue-line is expensive. Last season Caps were one of the worst teams among goals by D's. This season they are one of the best. Guess why?
They needed that threat and production from the blue-line, more so now that Carlson is closer and closer to retirement and propably needs to tone down his minutes as years go by. Our D is brilliantly built and has just about everything you'd want but take away Chychrun and the goal threat is gone. There aren't cheap fixes on that regard, unless you aren't banking fully on potential.
Could have always let him walk and gone after the next best D in the market in that regard. Here is the list, and their goal totals:
Jakob Chychrun - 18 goals (missed 5 games)
Neal Pionk - 9 goals - 5.875m AAV this season (missed 6 games)
Ivan Provorov - 7 goals - 6.750m AAV this season
Nate Schmidt - 5 goals - 0.800m AAV this season
Alec Martinez - 5 goals - 4.000m AAV this season (missed 29 games)
Dmitry Orlov - 5 goals - 7.750m AAV this season (missed 5 games)
Dante Fabbro - 5 goals - 2.500m AAV this season (healthy-scratch for a while)
Brent Burns - 5 goals - 8.000m AAV this season
Schmidt turns 34 this summer. Martinez turns 38 this summer. Orlov turns 34 this summer. Burns already over 40. Fabbro is younger but in the last 3 years he has 2, 3 and 2 goals.
I think we are going to be happy with this contract when we see the kind of contracts some of those guys are going to get in the summer. Pionk and Provorov are going to get paid, likely atleast around 6m per. In terms of value, Schmidt would propably have been the best option but he has about 30% of Chychrun's goals. In terms of goal threat that'd be like replacing Ovechkin with a Taylor Raddysh.