I think you should always take who you think is the best player, regardless of position or slot money considerations, unless you have 2 or more players rated very similarly, which could be the case at pick #4, this year.
That being said, I hope the Sox rate a college pitcher highly enough to take at pick 4. If they take someone else, I'll trust they know more than I do or even all the mock draft sites.
I will add something about catchers: catching prospects are probably the hardest to "get right." Some that are "gotten right" end up being moved to other positions.
Although I often frown on anecdotal evidence, like the case of Roger Clemens, think of all the highly or somewhat highly rated young catchers we've had in our system (some by trade) who flopped (some moved up after being drafted by showing promise in the minors or early majors- I won't add Salty to this list):
Kole Cottam (130th pick in 2018.)
Austin Rei (81st pick in 2015.)
Jon Denny (81st pick in 2013.)
Swihart (26th pick in 2011- man, that was THAT long ago?)
Lavarnway (was a 6th rd pick, though with Federowicz taken the next rd.)
Kottaras (PTBNL in David Wells trade, and he actually went on to put up some decent numbers in MLB after being waived.)
Schoppach (The one we got right: we traded away. 2nd rd 2001.)
Marzano (taken in first round back in 1984)
Marc Sullivan (2nd rd in 1979)
Note: We did take Carlton Fisk in the first round in 1967, and that worked out well, but that was so long ago.