The Pirates are almost finished adding this offseason. In fact Spring Training is here, so IMO the offseason is over. It seems like the Bucs lineup is complete against LHP unless they add an everyday player before Opening Day.
The Bucs lineup is more concrete against LHP since many of the Bucs players hit LHP significantly better than the opposite hand. Players in this category include Nick Gonzales, Tommy Pham, Joey Bart, Ke'Bryan Hayes, and Andrew McCutchen (except for last year). Bryan Reynolds and Oneil Cruz hit righties better, but they are the Bucs best hitters overall and will be in the lineup. IKF has basically an even spread against lefties and righties. He is expected the be the Bucs everyday SS.
That leaves one more open position to field 1B or Outfield depending on if Reynolds gets reps at 1B. I think that position will go to Billy Cook. I think Nick Yorke still needs some work against horizontal break. In AAA he hasn't shown a major weakness, but if he does have any weaknesses in the box it is the slider. Yorke actually saw the highest percentage of sliders relative to other pitch types than anyone else mentioned in this article last year while Cook has seen the highest percentage of 4-Seamers relative to other pitch types. It just seems teams have a better idea on how to get Yorke out than how to get Cook out. However, Cook has a strong chance to whiff on any pitch including the 4-Seam where Yorke does not. The best way for Cook to reduce that weakness is to face major league pitching while it seems Yorke can still season in the minor against the horizontal break. Yorke is also considered a top 100 prospect in some outlets, and if he can't get everyday reps in the majors he probably won't be there. Cook on the other hand the Pirates want to get his glove on the field and probably are more receptive to playing in a platoon.