the term optional assignment is pretty misleading. it's from the team's perspective, not the player's. had choi not been added to the 40-man roster, he could've opted out on two different dates. he'd still have a minor league option remaining, which as we saw in the case of keon broxton, can end up working against you. thus, any team that signed him to a minor league deal could keep him off the 40-man roster, and upon adding him, could keep his minor league option preserved if they did not option him, or kept him optioned for 20 days or fewer in 2018. this is obviously easier to do as the season wears on (especially in august, right before rosters expand in september). if choi ends up being optioned, i'm certain he'll be celebrating when 20 days have passed, because then he'll enter 2019 spring training without any options, which typically forces a team's hand to keep him. so, slight advantage to choi in that he gets a higher salary as a 40-man roster player in his third option year, and in that all indications are that he will burn his final option in 2018.