Blocked passes and takeaways are about as useful in analysis as blocked shots or hits. They can tell a story but most of the time they’re just noise as all arenas track them differently and so much is missed by those tracking them.
Corsi % as a raw stat with no context is completely meaningless. His high corsi % is more driven by his offense than defense. His relative xGA is basically 0 which means defensively Vegas is no better or worse off without him on the ice despite him getting favorable deployment (60 percent of his starts are in the offensive zone). He doesn’t penalty kill either. I would say that’s fairly one dimensional. I’ll give him credit though, he’s very good at that dimension.
And stats aside I actually watch Vegas quite a bit. He definitely has improved defensively but his compete level is still off at times, he’s lacklustre in front of the net and can be way too casual moving the puck which results in bad situations. He’s gone from being a trainwreck in his own end to below average but he’s still not someone I want out there protecting a lead late in the game.
Well stats aside, as you make fair but somewhat arguable points, I'd say you're not totally off the mark with the criticisms in the third paragraph. He does have his lackadaisical moments at times and isn't much of a crease clearer. I disagree about the casual puck moving. Sure he has stinker passes every now and then (but so does literally everyone on the Vegas roster and they still manage to have some of the best O-zone rel to d-zone possession in the league) but he's generally the most reliable player on the team at zone exit passing.
All the same I'd say he's certainly not elite or what you can call 'strong" defensively but I'd agree to disagree that he's below average and certainly continue to protest that he only has one dimension. As Vegas' defense goes I trust him far more in his own zone than anyone not named Schmidt or Martinez. Personally I'd say he's very slightly above average in his own zone. I don't look at him and think he's one of the liabilities or worry much when I see him defending. McNabb, in spite of a penchant for making big and timely defensive saves is far more likely to blow coverage. Whitecloud shows promise but has the same level of consistency as McNabb which isn't terrible for a rookie. Holden, Merrill, and Engelland in respective ranked order tend to be nightmares in the d-zone far more often than they have competent nights. Engelland in particular may as well be retired at this point. He lost Gallant's trust and DeBoer hasn't given him a shot.
Rambling aside, to me, offensively one dimensional defines a player who is a talent on offense but an active liability or at the very least a low to non factor defensively and I don't agree that Shea falls into such a category. You can say a guy like Teemu was one dimensional. Not Theodore.