This only judges a player's hitting season.
10. Daniel Palka
In only 93 PA, Palka had a WAR of -1.1. Through his first 12 games, Palka was slashing .000/.129/.000 with 0 HR in 39 PA. The next game, he collected his first hit of the year, but it was too late. He was sent down to the minors, where he spent most of his season. He came back, and was still pretty horrible except for one game where he hit 2 HR.
9. Keon Broxton
A good fielder who isn't really known for his bat can struggle. But in Broxton's case, he struggled so heavily that, well, he was worse than Chris Davis. With 3 teams in 2020, Broxton slashed .167/.242/.275 with 6 HR. He was one of the worst players in the league.
8. Travis Shaw
Shaw was a really good hitter in 2017 and 2018, but in 2019 he was the most disappointing player in the league. He hit .157/.281/.270 with 7 HR in 230 AB. He was so bad that the Brewers sent him down to AAA where he dominated, but the damage had been done.
7. Ryan O'Hearn
This slugging DH was just given a ton of PA, so his oWAR was obviously down. But don't let that fool you. He hit .195/.281/.369 with 14 HR in 370 PA. Would you trust him to be in a big situation? I know I wouldn't, and the Royals didn't sending him down to AAA.
6. Zack Cozart
The once All-Star Zack Cozart struggled so much that he slashed .124/.178/.144 with 0 HR. He was so bad that I almost raised his rank to Number 1, but he only had 107 PA. He'd better step up his game, or he's going to be out of the league in no time.
5. Max Stassi
This catcher struggled so heavily in his 147 PA, that the Astros sent him down to AAA. For 2 teams in 2019, Stassi slashed .136/.211/.167 with a measly 1 HR. And the worst part is that he hit .071 for the Angels in 2019. Step it up, Mr. Stassi.
4. Chris Owings
In 2019, Owings slashed .139/.209/.233 with 3 HR with 2 teams. That gave him an oWAR of -1.3 Nice job, Chris! You'll be back next year! He was sent to the minors in 2019, where he was pretty good. Maybe he'll be back at the MLB level, but you never know after a season like that.
Before I reveal my top 3, let me give you some honorable mentions.
Honorable mentions: Chris Davis, Mac Williamson, Tyler White, Josh Harrison, and Jose Peraza
3. Martin Prado
Prado's age 35 season was so bad that he decided to retire at the end of it. Prado slashed .233/.265/.294 with 2 HR. Talk about a retirement tour! Maybe a retirement bore for Martin Prado.
2. Lewis Brinson
In his career, Brinson has been nothing but bad. After his 2018 season, I thought that it couldn't get worse. But it did. He slashed .173/.236/.221 with 0 HR. Heck, he was so bad that he spent the majority of his season at AAA. Hopefully he'll improve for 2020.
1. Jeff Mathis
Mathis is as bad as it gets, hitting wise. A stellar defensive catcher, Mathis slashed .158/.209/.224. He was the worst hitter in the MLB in 2019, and he had a -1.9 oWAR. His career total WAR, according to Baseball-Reference is 0.0. That's sad. He's sad. I'm sad.