Giants' Logan Webb Admits He Pitched In MLB All-Star Game Wildly Hungover

We now know why Logan Webb pitched poorly in the MLB All-Star Game earlier this summer ... he just admitted he was wildly hungover as he was toeing the rubber at the Mid-Summer Classic.

The San Francisco Giants star made the revelation on Wednesday's episode of " The Chris Rose Rotation " ... explaining that he went just a little too hard in Arlington the night before the big July game.

He said following the Home Run Derby festivities on Monday evening -- the MLB threw a party for the players and their families at the Dallas Cowboys' The Star facility ... and there was a ton of free booze.

He said Lil Jon was also DJing ... and it all made for the perfect combination of a late night.

To make matters worse for Webb, the ace said his wife woke him up at 7 AM on Tuesday morning -- some 12 hours before the game's first pitch -- and it was at that time that he says he knew "this is going to be a long day."

"And it was a long day," he said with a laugh.

Webb told Rose it was over 100 degrees during the afternoon ... and by the time he was running out to pitch in the third inning for the National League -- he wanted to vomit. In fact, he said he had to tell himself repeatedly, "don't throw up" on his way to the mound.

Webb ultimately got three American League hitters out -- but he gave up three hits, three earned runs and one walk. The NL would go on to lose the game, 5-3.

Overall, though, he said he had a great time during his first-ever All-Star Game experience -- but, if he gets another selection down the road, he said he will change one thing ...

"Just relax the night before," he said.