Truly I don't think the position matters as much as the "lefty killer" with power part.
With Varsho coming back soon, that pushes Straw back to the bench into his PH/PR late inning defensive replacement role with the occasional start when Varsho needs a day off. That's really where he should be since his defense is only a sliver worse than Varsho, but his bat is an entire forest away.
Current 40 man roster guys (assuming all healthy) that can play the OF - Loperfido, Clase, Lukes, Robertson, Roden, Santander, Springer, Schneider, Straw, Varsho, Barger.
Eliminate the lefty hitters and you have Clase, Santander, Springer, Schneider and Straw. Clase certainly isn't much of a killer of anything except hope... Santander is a ? atm, Springer is hitting like Judge, Myles has a Straw bat, and Schneider has been doing everything possible to show he can be that guy.
On the IF - Barger, Schneider, Bo, Clement, Gimenez, Jimenez, Vlad, Orelvis and Wagner. Orelvis is a non-factor right now. Scratch the lefties again and Clement is a lefty killer but with limited pop so you can easily plan on his numbers regressing a bit. Bo is always gonna be in the lineup when healthy, Jimenez is a 125 wRC+ against LHP in his MLB career, and has always hit LHP well in the minors but like Clement, very limited power output.
Right now, the only real power threat from the R side that wouldn't be in the lineup everyday is Schneider, and even with his current hot streak, he's far from a sure thing power-wise.
Anyways, all of this rambling aside, there's enough guys on the roster that can play both IF and OF, and we have enough LHH and SH, that all we really need as a hired gun to hit from the R side and launch nukes off the bench, position doesn't really matter so much.