Dave Dombrowski has made few mistakes since becoming president of baseball operations of the Red Sox in 2015. Three playoff appearances and last season’s World Series championship attest to that.

The glaring exception was the Dec. 6, 2016 trade that sent infielder Travis Shaw and three prospects to the Milwaukee Brewers for righthanded reliever Tyler Thornburg.

Shaw has since had an .844 OPS in 296 games for Milwaukee, with 63 home runs and 187 RBIs. Thornburg missed all of 2017 recovering from thoracic outlet shoulder surgery and last season appeared in only 25 games and had a 5.63 earned run average and 1.58 WHIP. But Dombrowski isn’t giving up on the deal. The Sox on Friday signed Thornburg to a one-year contract worth $1.75 million, with incentives worth a potential $400,000. The incentives are tied to appearances.