The rebuilding Phillies have locked up one of their core players for at least another five seasons.

Outfielder Odubel Herrera, a former Rule 5 Draft pick, has signed a five-year contract extension that includes a pair of club options. Herrera will reportedly receive $30.5 million guaranteed as part of the deal, according to Matt Gelb of the Philly Inquirer, with the chance to make an additional $24 million, depending on if his options are exercised:

The motivation behind the deal is clear on both sides. The Phillies have now locked in costs on a talented 24-year-old center fielder -- one with a 111 OPS+ over his first two big-league seasons -- while also extending their control over him by up to three additional years. Herrera, for his part, trades his earning potential for earning certainty, all the while making his first fortune.

Herrera has been one of the best Rule 5 picks in recent memory. He made his first All-Star Game last July and has hit .291/.353/.419 for his career. Depending on how much you trust defensive metrics, you could make the case he's been worth about eight wins above replacement -- for perspective, that ranks seventh among center fielders.

What's more impressive is that Herrera grew as a player in 2016. Compared to 2015, he improved his strikeout and walk rates, his power production, and his stolen-base ability. Those are promising signs for someone years away from hitting his prime.

If Herrera can maintain those gains, he's going to be severely underpaid throughout the life of this extension -- as opposed to just underpaid. After all, center fielders who can double as legitimate leadoff hitters are always in demand. All the same, you can understand why Herrera took the deal; no matter how talented, no matter how young, it's difficult to pass on a guaranteed $30 million.

On the Phillies' side, it's worth noting this is the first (and therefore only) guaranteed salary on their books for the 2018 season. You can bet it won't be the biggest when it's all said and done.