It's not a good time for a player to endure a horrible injury like Trevor Story just did. The Boston Red Sox star fractured his shoulder and is expected to have a six-month recovery period following surgery. He'd be lucky to return for the end of the regular season if all goes well, so while it's not quite season-ending, it's difficult for a team to withstand.
It's a bad time for this because Trevor Story replacements aren't easy to find. The free agent market is bare bones, and it's generally too early to swing a trade. The Red Sox are surprisingly second place in the AL East now, so it would behoove them to try and keep Story's absence from derailing their hot start regardless.
Trevor Story replacements for Boston Red Sox
3) Adalberto Mondesi
Adalberto Mondesi has something that a lot of other options don't: speed and youth. He's only 28, making him a much younger option than the vast majority of options on the free agent market. He hasn't been able to hit consistently well at the MLB level, but the former Kansas City Royals star might be a worthwhile defender and is a quality base runner that could at least try to fill in for Trevor Story.
2) Donovan Solano
Among free agent options, the only one there that has proven to be able to hit recently is Donovan Solano. The former Minnesota Twins star hit to the tune of a 110 OPS+ the last time he was on a roster. He doesn't provide a lot of defense, but he can hit better than the majority of the realistic options out there. He would also be quite cheap and can play multiple positions.
1) Jorge Mateo
It's early to try for a trade and it's not very likely that the Baltimore Orioles will want to swing a trade to try and help their divisional rivals, but the Orioles have a wealth of infielders. With Jackson Holliday about to force his way to the MLB level, they will soon have even more. Jorge Mateo could be exactly what the Red Sox need, though it might cost them a pretty decent haul. Mateo is a good defender, capable hitter and good base-runner. The only problem is that it's April and he plays in their division.