Jack Warhop was not a bad pitcher. You don't play seven full major league seasons if you are outright bad. He even made the Pinstripe Alley Top 100 Yankees list. He was pretty good. It's just that in the seven seasons he played, Warhop accomplished something rather amazingly bad.
After a couple impressive minor league seasons, including two with the gloriously named Freeport Pretzels, Warhop made his major league debut for the then New York Highlanders in 1908. Warhop appeared in five games that season. In 36 innings, he had a 4.46 ERA, which was a 56 ERA+, so not great.
The Highlanders kept him around, and in 1909, he had a pretty good year. He lowered his ERA to 2.40. It was the Deadball Era, so that's not as impressive, but still. It was enough to ensure that Warhop would be a fixture for the Highlanders/Yankees for the next couple years.
He did lead the league in one category the 1909 season: batters hit. Warhop hit 26 batters in the 1909 season. For comparison, four players tied for the 2015 lead with 13, exactly half of what Warhop did. He pitched 243.1 innings that season, so he essentially hit a batter every nine innings. Second in the league that season was Cy Morgan with 22, but in 50 more innings.
The next season, he managed to reduce his hit batsman total to a paltry, league-leading 18. That season, he tied with Cy Morgan for the league lead. In 1911, Warhop fell well short of Morgan's league-leading 21, only managing 15. Their HBP duel would end after that season, as Morgan pitched just 96 more innings over the next two seasons.
Meanwhile, Warhop would never again lead the league in hit batsmen. That didn't mean he wasn't plunking people at an impressive rate. In the remaining four seasons of his major league career, he hit 16, 12, 11, and then 12 batters. For his career, Warhop hit more people than he allowed home runs. Again, it was the Deadball Era so that's not so crazy, but it's not remotely close. Warhop hit 114 batters and allowed just 28 home runs over his seven seasons.
In the PSA Top 100 post about Warhop, Andrew unearthed this quote:
"(Jack) Warhop has not the size or strength to strike a ball down the groove with (Walter) Johnsonian speed. His fast ball and curve, though fair, are not extraordinary, but the way he mixes them with his slow ball - combined with his extraordinary control - would make him a valuable asset to any club." - Baseball Magazine (Ray Istorico, McFarland Publishing, 02/28/2008, Greatness in Waiting: An Illustrated History of the Early New York Yankees, 1903-1919, 'The Unluckiest Pitcher in the League, Page 148)
He has the 33rd highest BB/9 of any Yankee ever, so "extraordinary control" seems a bit hyperbolic, but he's not even close to the worst in baseball in that period. He wasn't some wild, crazy pitcher with no control, he just hit a bunch of people.
From 1908 to 1915, the years in which Warhop played, he is the leader for most batters hit with 114. There are only two people remotely close to him. One is Walter Johnson with 102. Johnson pitched nearly double the innings Warhop did in that period. The other is Ed Willett with 101, and he faced nearly 1300 more batters than Warhop did. Cy Morgan played in a similar amount of games to Warhop over three more seasons, and finished with only 95 batters hit for his career. Warhop is 33rd all-time in baseball and everyone ahead of him has pitched at least 400 more innings.
Jack Warhop was a pretty decent pitcher for the early Highlanders/Yankees' team. It's just that for whatever reason, he hit a ton of people.
All data courtesy of the Baseball-Reference Play Index