There is a large difference between an early 2nd round pick and a late 2nd round pick. Usually teams have players with 1st round grades in the early 2nd, but by the time they get to the late 2nd those players are usually gone. The Avs have done very well drafting in the early 2nd, but when they get past ~40 their record is not so good. Gaunce, Delmas, Elliott, Pickard, and Heard were all 2nd round picks after #40 since 2008. Not exactly a bunch of world beaters.
Now people argue value frequently on 2nd round picks, well out off all the draft picks, 2nds are probably the most dealt right now and their value differs wildly between expected positioning and teams get far different returns. Murray cost 2 2nd round picks (Pittsburgh so late 2nd round), whiile Sekera cost an early 2nd round and McBain (also probably worth a 2nd round pick at the time). Peter Holland cost a conditional 2nd round pick. Setoguchi cost a 2nd round pick. Rundblad (who is very close to being a bust) cost a 2nd. Regehr cost 2 2nd round picks. MacDonald cost a 2nd and a 3rd. Andrei Kostitsyn cost a 2nd and a 5th. A number of those would be considered 'bad' trades.
Now it probably was a bit of an overpayment, but the amount of that overpayment is not that large. Make it a conditional 3rd (say 3rd if under 50 games, 2nd if over), and it would be much closer to 'correct' value. Without a doubt I would much rather overpay by 1 round to avoid the hot mess that was UFA defensemen this year. There were some seriously ugly contracts for players that are not any good. Right now the Avs have a stop gap for a year and can walk away if this doesn't work.