He's played his entire career on a team that struggled mightily to score at even strength, not his fault. I remember a few short months ago when everyone was telling Sabres fans ROR was a "PP specialist" because his ES production was poor in Buffalo. Now look at his ES production in St. Louis.
Risto's #1 problem historically has been that he's been asked to play a role that maybe 5 D in the league are capable of being successful in, and he's been asked to do it on a poor team with partners who, at their very best, might be considered NHL #4 defensemen. It's not a coincidence that Risto's looked better as Dahlin's earned more minutes and the team around him has improved. He's not an all-situations #1, but he's a good hockey player.