He looks so different with that short hair! He is styling it really weird. Also, the hair looks reddish?!! Or maybe its just the filter the instagram user used. Vernon in the book is supposed to have yellow (blonde) hair.
This being Alex, when it's this short his 'styling' probably consists of towel drying it and running a brush/comb through it.

As for the color, looks like the dark blonde it usually gets during winter.
Precisely.
Obviously, I've always thought his acting was impressive, but his performance has been mind-blowing.
His acting really has been noticed for this, which is nice for those of us who thought he's been a good actor all along.
Celeste’s exhilaration, then, makes perfect sense, especially as she’s in a situation where she has likely felt trapped. There are few better feelings than to believe you’re doing a good job as a mother, but victories in professional life, with people we aren’t actually related to, resonate strongly as well. That whole meeting scene was nicely done, with Renata facing off against Celeste and Madeline on the other side of the table, Madeline’s feeble attempts to go off, the attempted down-home regular-guy efforts of the mayor, and Celeste’s ultimate complete command of the entire situation.
It’s that power aspect that Celeste’s husband Perry most objects to.
Such is the acting chops of Alexander Skarsgård that we start to tense up now pretty much every time he enters a room, he’s steeped in so much menace. This episode deftly played that up slowly, until the final grab at the end. Celeste is saved by one of her sons, who must be taking in much more than they realize.
http://www.avclub.com/tvclub/big-little-lies-wages-mommy-wars-251926
I've seen this in viewer comments over the last couple of weeks, that Perry enters a scene and they tense up because they don't know what he's going to do.