I've had a few guys that are right on the cusp of 50 for VsR (49,48) that were off an on effective. That being said, they all had control in the high 80's with their first two pitches bordering on 90's. Even still, those guys were (as Mike would call them) 1 arb guys. Also helps that my main squad plays in San Diego, so I can get away with a lot worse pitching.
This is only because I have 2 SP on the DL but this guy has been able to hold his own in the majors.
https://www.whatifsports.com/HBD/Pages/Popups/PlayerRatings.aspx?pid=6819835
Its a catch 22 because you can have a hitter who has VsR <50 if their other stats are good, contact, eye, or if they have a high VsL. I had a defensive catcher who had a VsR of 0 and still hit close to .300 for a couple of years because I only had him start against left handed pitching.
For pitchers its harder, even if you have them come in to face a left handed batter, chances are there will be a few righties before they get taken out of the game which will cost them. The opposite itsn't always true.