Interesting trade. From Ottawa's perspective, I like that they are actively fixing a dysfunctional situation. It was a bad trade with Phoenix but that doesn't mean that they must waste another season just to try and save face. Rip off that band-aid.
Jensen was a rock solid player for the Caps with exceptional skating ability until last season but his play DID crater. Maybe there was an external reason, maybe there wasn't. He is at an age when decline should be expected. As another poster mentioned, Jensen takes a very long time to acclimate to new system/teammates. That's a negative for Ottawa.
Chychrun is one of many former Arizona players that we all assumed were somewhat held back by the team but are simply not as good as once thought. Considering his contract, it's a small risk to take for the Caps. One troubling aspect is that Chychrun is a left shooting D who scored 16 power play points last year and that number is likely to plummet on an Ovechkin based power play. There has never been any room there for a left hand D and that's unlikely to change.