Remember ... the Washington Wizards star threw arguably the worst first pitch in MLB history about seven years ago ... and, unfortunately, he's not much better with a bat in his hands.

Wall was at Nationals Park warming up for the MLB celebrity softball game Sunday night ... when he took some BP.

If you're counting at home ... that was three fouls, a complete whiff, and maybe a base hit -- all from a dude throwing lobs from about eight feet away!!

Wall's confidence wasn't shaken ... he was somehow able to hit a single and score a run when the bright lights actually came on -- but, still.