Yeah, to be fair, even though Hoskins is a lot younger, he's a bigger guy. BBref lists Hoskins at 6'4", 225lbs while Santana is 5'11", 210lbs.
Both have some SBs, Santana with few more than Hoskins, both with SB/CS ratios that suggest neither one of them should be trying to steal bags.
I agree with the suggestion (made in the Galvis thread) that the Phils might also be hedging their bets on Hoskins, which IMO is reasonable. If Hoskins struggles, it’d be good to give him much time off to clear his head. But without Santana, who’s the backup 1B, Joseph? Franco? With Santana at 1B and Hoskins in the OF, it’s much easier to give Hoskins some days off or even send him back to AAA for a bit if needs be. The Phils needed a backup 1B anyway and they just took the unexpected route of giving that role to Hoskins without taking his bat out of the lineup.
If Hoskins tears the cover off the ball but embarrasses himself in LF in 2018, the Phils can eat half of Santana’s salary, trade him in the offseason, and reinstate Hoskins at 1B for 2019.