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Scott MReading that article reminds me of the addage that the more things change, the more they stay the same.. Who would of thunk it.. players dogging it even back then 
A quick internet search on sock and buskin reveals that its a term that goes back to the early days of theatre when bands of Greek traveling actors would wear particular footwear to denote the type of play they were presenting - socks in the case of comedy and buskin (big boots) in the case of tragedy (taken from the website of a theatre company in Canada which goes by that name).
The burnt cork reference also appears to have its roots in early theatre and traveling minstrels based upon a google search.
If the article was written today I would imagine that it would read that "ball players are as open to criticism as movie stars and rock stars..."
Considering what they make, the logic holds just as true today as it did in 1881