The prime example is the disastrous five-year, $125 million extension the Philadelphia Phillies gave Ryan Howard in 2010 when he still had two years left on his deal. Howard was a former NL MVP who finished top-five on the ballot in four consecutive seasons leading up to the extension. He finished 10th in MVP voting in 2010 and 2011, the last two seasons of his original deal.
Howard suffered a devastating Achilles injury during the 2011 postseason, leading to the early demise of his career. He returned to play in 71 games the following year but clearly wasn’t the same hitter and never was again.
Howard produced a brutal -1.2 WAR in the first year of his new deal and was a shell of his former self for the rest of his career, which mercifully came to an end after the 2016 season. Howard hit .226/.292/.427 and produced -4.5 WAR over the five years that covered his extension. He had a sub-.800 OPS in each of those seasons and never topped 25 home runs in any of them.
The injury played a significant part in Howard’s decline but he never came close to recapturing his previous form once his Achilles recovered, by which point he was approaching his mid-30’s. It’s fair to say his next contract would have looked a lot different had the Phillies waited until Howard was eligible for free agency.