Before the 2015 season, the A's and Royals each signed a new designated hitter to a multi-year deal. The A's chose a 29-year-old former All-Star who'd just had a slight off-year (96 OPS+) on a pennant-winning club. The Royals chose a 32-year-old who'd just had a massive off-year (75 OPS+) after missing months to a contract holdout, and he also carried a significant injury history. The A's guy flopped (98 OPS+) for a last-place team, while the Royals' guy enjoyed the second-best year of his entire career (127 OPS+) and was a key figure in a championship run.
We can (and frequently do) second-guess Oakland's decision to give Billy Butler a three-year contract, especially since the Royals only needed to commit to two years to sign Kendrys Morales.