CD: Can I ask to clarify something you just said: If I understand correctly, to get tickets for friends & family, MLB players now purchase from website. I assume that means they pay with credit-card, debt-card, paypal or something? In that case, there's no additional tax liability created. The players are purchasing the tickets with their after tax dollars It's the same as if you or I were buying tickets for a game.
In the prior situation, where the front-office was handling tickets - Player tells someone on Team admin they need X number of tickets for a game - then the player is getting a benefit/compensation that will be taxed: The value of the ticket(s). In that situation, then yes, the player who got a 1,000 tickets over the season would infact have gotten a $40,000 benefit from his employer and would be responsible for taxes of that benefit (either via paycheck withholding or via filing process).
There is one edge case here: If the MLB player's website sells the player's deeply discounted tickets, then the player would be on the hook for the income tax on the benefit between the price paid (ie. the $40) and the fair-value the tickets. Again, total edge case: In practice, I imagine the price the players are paying is considered the value of that ticket.