The itemization could be enough to recoup some back, depending on any money (not just for baseball) earned that year and how much you pay towards your fed and state taxes.
Other items are anything else that you spent that would be related to your job. Supplements, vitamins, gym fees, dry cleaning, car transportation, spring training meals and expenses, not paid by team, any travel expenses while traveling during season, not covered by team just to name a few.
If you spend one season in one place, you cannot take off rent, food, etc, IRS considers that your tax state, if you get moved up during the season, you get to take off all expenses where you spent the least time that season (as related to your job). That's what I get out of it and club dues can be very much apart of those expenses. For example, while a player cannot always take off meals, he can deduct club house dues.
Some of it comes out in the wash though, son got a raise but now has to pay MO state tax, where he didn't here in FL.