Why do the BoSox batting helmets look like they’ve been through a fire? I mean, emotionally and all that, the BoSox probably feel like they’ve been through the fire, but what happened to their helmets?
Pine tar. They get it on their batting gloves, then adjust their helmets.
Of course, helmets can be cleaned, but some players appear to be superstitious about it (or have some other reason for liking their domes that way).
Here’s a column in the Pittsburgh Post-Gazette from July that talks about it.
Some of the Red Sox seem to have an exceptional amount of it. They seem to be cultivating a “Filthy Phils” kind of mystique. They look like a squad of Klingons.
So glad I wasn’t the only person who looked at those helmets and thought WTF?
With the explanations, it makes sense. Guys in the fire service like to get their helmets and gear as filthy as possible, and gripe when it gets cleaned. Kinda like your dog that is fresh from the groomer, and runs out back to roll in something evil. 
Thanks for all the replies - interesting.
The reason I noticed it was the contrast with the Yankees - none of them had such dirty helmets, although they weren’t exactly shining clean. Different team customs, I guess.
Can someone explain the use of pine tar? Have you ever touched that goo weeping from a pine? It’s messy as all get-out. I WAG the professional stuff is refined, but heck…I can’t imagine dealing with that guck.
I don’t even enjoy being sticky while trying to enjoy a pancake breakfast! So, just how gooey is that stuff? Doesn’t it bug the pros? And, why do they even need it? For $MM, you’d think they could at least hang on to a bat! - Jinx
For a couple of bucks you can make your job a lot easier. 
Also, when the ground is wet, runners on base will often hit their helmet against their cleats (after removing the helmet of course) to knock some of the dirt out. That tends to beat up the helmet as well. In game 5 or 6, Cabrera did it hard enough that the onfield microphones picked it up clearly. He’s probably got the nastiest helmet of the bunch.
Pine tar. So that’s it. I thought it looked like someone left a burning paper pag on their doorstep, and they used their batting helmets to put it out.
It probably didn’t start this way, but it’s made for a good contrast against the Yankees, who are clean-shaven, short-haired, and basically are made to look like Boy Scouts by Steinbrenner. The Sox are the down and dirty, beat-up underdogs looking for a fight.
And by tar, it worked!