The Boston Red Sox floated multiple potential return dates for Triston Casas over his nearly 100 days of rehab. Finally, he began his rehab assignment on July 30 in Worcester.

The first baseman has been sidelined with a rib cartilage injury since April 20. He initially hoped to play again the day his 60-day injured list stint expired, but setbacks have forced Casas’ timeline back over and over again.

The Red Sox recently reported that Casas was “far” from ready for a rehab assignment and his return to the big-league roster would take a few more weeks. Just days later, the first baseman turned a corner and has taken batting practice at full speed. He’ll likely need a long rehab assignment before he’s reactivated to Boston’s lineup, but the end of Casas’ recovery nears, if all goes according to plan.

Boston has slumped after the All-Star break but it had been on a tear since the beginning of June and the team’s chemistry was palpable. It’ll make the corresponding roster move to Casas’ return even more difficult.

The Red Sox signed Dominic Smith to play first base in Casas’ stead over his IL stint, and he’s been a solid replacement. He’s slashing .225/.316/.363 with 13 doubles and five homers in 54 appearances. Smith has made five errors in 49 outings at first base, but his gaffes tend to come in waves and he’s been more consistent than the numbers indicate.

Boston could designate Smith for assignment to reinstate Casas in a one-for-one move. After his injury, it’s unlikely Casas will play every day when he returns, but Romy González is a capable first baseman who can play well in other positions when the Sox need him. He also has better offensive numbers than Smith and hasn’t made an error at first in his 77 innings there all year.

The Red Sox could swap David Hamilton for Casas. The infielder has put together much more consistent performances since the Sox’s error-riddled stretch in April and June, but his defense is still questionable relative to some of Boston’s other options like González or Vaughn Grissom.

Hamilton swung a hot bat for a good stretch of May and June. At best, he batted .289/.344/.446 on June 11, but his offensive production has stalled lately. He’s slashing .221/.280/.314 in his last 30 games.

Smith and Hamilton are both lefty bats, and Boston’s batting order is packed with left-handed hitters. González is right-handed, which is hard to come by in the Sox’s lineup, and it probably makes him the preferable choice to stick around in the big leagues.

Casas still won’t be ready to play for a few weeks, and a lot could change before then — hot players could stall out, and vice versa. But for now, Smith and Valdez seem like the obvious choices for the impending Casas roster swap.