Last few times Dotchin was in, he would play one decent game then relapse into boneheadedness. They also don't seem to try him with anyone other than Hedman. I was thinking Coburn/Dotchin might make a physical forward-smashing duo, but you need to have at least one decently fast skater on a pair. And weirdly enough, I actually trust Girardi with Hedman over Dotchin.
McDonagh obviously has talent and experience but he's got to get out of a Rangers style defensive mindset. Strålman can help with that if Mack is willing to adapt to his new team. Funny, but there's a bunch of Rangers fans who wanted to see a McDonagh/Strålman pairing while Stråls was still with them.
Edited to add: and yeah, some of our forwards seem to forget that defense isn't just up to the d-men.