The Jackie Bradley Jr signing
The main thing keeping the Jackie Bradley Jr signing from being declared the worst move of the last decade is the fact that the Brewers were able to get out from under his contract after just one year and acquire Hunter Renfroe for him in a trade with the Red Sox.
At the time, Jackie Bradley Jr was the best free agent left on the market as spring training got underway. The Brewers already had a full outfield but decided to bring in Bradley on a two year, $24MM deal with a mutual option for a 3rd year and a player option on the 2nd year.
Bradley proceeded to put up one of the worst offensive seasons in living memory. He hit just .163/.236/.261 with a 35 OPS+. League average OPS+ is 100 by the way. This signing was a disaster, but somehow they were able to salvage some trade value and send him along with two prospects back to Boston for a productive hitter in Hunter Renfroe. Not having to see another season of Bradley attempting to hit in a Brewers uniform saved this move from being the worst of the decade.
Signing Matt Garza to a 4 year contract
Brewers owner Mark Attanasio wanted to make a splash. Matt Garza was a hot commodity at the trade market in July and he had pitched well for the Cubs for the last couple of years. So, right before Brewers On Deck in 2014, they signed Matt Garza to a four year, $50MM contract.
However, the Brewers didn't expect Garza to fall off so quickly. He put up solid numbers in 2014 with a 3.64 ERA in 163.1 IP, but it went downhill fast after that.
Garza had an unsightly 5.63 ERA in 25 starts in 2015, followed by a 4.51 ERA in 2016 and a 4.94 ERA in 2017. The Brewers eventually demoted him to the bullpen, which he didn't like, and he was sent home before the season was over. Garza struggled so much that even though the Brewers entered a rebuilding period in 2015 and traded away as many veterans as they could, no one would take Garza. They couldn't move him.
One year was good, three years were bad and the Brewers were stuck paying the rest of his contract.