Number 1: Chan Ho Park
There should be no doubt about Chan Ho Park being number one on this list. Alex Rodriguez in his first off-season with the Rangers helped influence the front office to get this done. Park in 2001 was the top free-agent pitcher on the market, but the question should have been if he was an ace or more of middle-of-the-rotation pitcher.
Park had won double digit games from 1997-2001. One concerning aspect that the Rangers should have given more consideration was that he was prone to giving up home runs. In those seasons mentioned he also gave up more than 20 home runs in each of those seasons except for 1998. He gave up 16 that season. He also gave up some of the famous home runs in MLB history. When Tatis hit two grand slams in the same inning they were both hit off of Chan Ho Park. When Barry Bonds broke the single season home run record and then added to it that same night they were both hit off of Chan Ho Park.
Park became a free agent after the 2001 season and signed a 5 year/$65 million contract that made him the sixth highest paid pitcher in all of baseball. He was brought here to be the ace Texas was looking for. The Ballpark in Arlington was one of the best offensive parks in baseball right next to Coors Field. The jet streams that would come through the stadium would take fly balls and turn them into home runs. Park in his 3.5 seasons with the Rangers could never figure out how to be successful in The Ballpark. He had a 6.00+ home ERA in 2002 and 2004. He never finished a season with an ERA under 5.00 in his time in Texas.
Texas traded him at the deadline in 2005 to the San Diego Padres for Phil Nevin. Park would go on to play five more seasons with the Padres, Mets, Dodgers, Phillies, Yankees, and Pirates. He retired after the 2010 season. He was brought here with so much hope and left with so much disappointment. His name was added to the long list of worst free agent signings in Texas Rangers history.