First, let me acknowledge that this is a very small sample size - the man had two appearances as a Cub. The point of this post is not to judge Hinshaw's entire big league career, but rather his brief Cubs tenure and compare it to other Cubs in terms of overall quality (or lack thereof). Pretty much all of the players mentioned here had very brief tenures as Cubs. (There can be some argument made that in terms of overall impact, Micah Bowie, Scott Chaisson, Chad Fox or even Lendy Castillo might be/have been "worse," but that is a discussion for another day).
Hinshaw's line with the Cubs, in case you have already tried to forget it it, is 2 G, 0.1 IP, 4H, 5ER, 1BB, 3 HR. His ERA+ is 6 and his ERA is 135.00.
According to Baseball Reference there have been 59 pitchers with ERAs in double figures. There have been two with three digits or more: Hinshaw at 135 and Mort Cooper.
Cooper was a four-time all star and the 1942 NL MVP who made one appearance for the Cubs in 1949 after a year-plus layoff due to arm trouble (April 14 article on his comeback). He pitched well, then was called up and on May 7 he came on in relief of Bob Rush with runners on first and second and surrendered a walk to Pee Wee Reese, a run scoring wild pitch followed by a single to Gene Hermanski, then a homer to Duke Snider. His line, 0 IP, 2 hits, 3 ER, 1 BB, 2 inherited runners scored - his ERA is infinite, his ERA+ is 6.
Only one other pitcher comes close in terms of ERA+ awfulness: Bob Smith in 1959. Smith, a career minor leaguer who had his MLB breakthrough season for the Red Sox at the age of 30 in 1958. For his success, he was rewarded with a trade to the Cubs by the Red Sox in Spring Training for Chuck Tanner.
On April 29, Smith came in in relief of Moe Drabowsky in the second inning. Moe had surrendered four in the first and opened the second by giving up a single to pitcher Brooks Lawrence and a double to 2b Johnny Temple. Smith came in and gave up a double to Vada Pinson, got Jerry Lynch bunting (as an aside, a bunt by the No. 3 hitter with a runner on 2nd with a 4-0 lead?), intentionally walked Frank Robinson (who then stole second), got Gus Bell on a groundout to the mound, then gave up four straight singles by Frank Thomas, Ed Bailey, Roy McMillan and Lawrence again. That was it for Smith, who was saved by the immortal Joe Schaffernoth. The Reds went on to win 18-8. The next week Smith was traded to the Indians for Randy Jackson, a 3b who was wrapping up his career. Smith pitched in 12 games with the Indians and had a 5.22 ERA. He didn't pitch in the majors again after 1959.
There are a few other awful performances of note. Larry Biittner came in to wrap up a blow-out loss to the Expos on July 4, 1977 in the first game of a double header and threw 1.1 IP, surrendering a walk and five hits, including three homers. However, he also struck out three batters (for the record, pitcher Jackie Brown, Del Unser and and Larry Parrish. The homers were by Ellis Valentine, Parrish and Andre Dawson). His 40.50 ERA is bad, but not bad for a Joe Mather-like position player.
In 1922, Uel Eubanks made a pair of appearances. His first appearance on July 20 was ugly, with two hits and a run. He didn't appear again until August 25, where he got lit up in a 26-23 win over the Phillies. The Cubs scored 10 in the second and 14 in the fourth, but surrendered 14 runs over the final two innings to make it close. Eubanks was a key part of that. The 19-year-old Texan entered the game with a 26-9 lead and was "ineffective" and let down by his defense. A walk, an error, a single, a walk, a sacrifice fly, another single, a sac bunt (really?!?!), another walk, another error and another single. When the dust settled, he surrendered three hits and three walks for eight runs, four earned. Bad, certainly, but no question the youngster was overmatched.
Honorable mentions for poor performances in multiple appearances go to a pair of guys who each played in the last 13 years. In 2000 Danny Young embarrassed himself in two countries, getting lit-up in Japan as the Cubs lost to the Mets, then getting battered in St. Louis. He went back to the minors and stayed there, then disappeared from baseball. Over his four career appearances covering three innings he has a 21.00 ERA with five hits and six walks.
Bad as that was, Andy Pratt was worse in 2004, though there was something noteworthy about his performance - he finished his career with a 21.60 ERA, but never surrendered a hit.
Pratt came to the Cubs from the Braves in 2004 and made the team out of Spring Training. His first appearance was solid, a mop-up inning with a walk and a strikeout in a 3-1 loss to the Reds. Two days later he sandwiched a pair of walks around two outs in an extra inning win over the Braves. But that was it for the outs in his career. The next five batters he faced over the next two games all reached (four walks and a HBP. He threw 18 pitches in those two appearances and managed one strike. One.) and he was banished back to the minors. In fact, Pratt pitched at every level in 2004, from Rookie to the Bigs. On Sept. 3 he was traded to the Brewers as the PTBNL in the deal for Ben Grieve.
So what is the verdict? Cooper was bad, but he was trying to come back from injury. Bob Smith was bad, but statistically, he wasn't as bad as Hinshaw and Cooper. Biittner was a position player. Eubanks was an outclassed 19-year-old. But Hinshaw came into his brief Cubs tenure with 88 games under his belt. It may turn out that he was injured, but based on the numbers and circumstances, I am here to declare Alex Hinshaw the owner of the worst Cubs "career" in history. YMMV.