In college, I inherited Mason Singleton and Stanley Brewster (both 5.0s and both playing for the Giants) at P and K. Both were pretty good, Singleton ended up winning the Ray Guy Award in his last year, and Brewster was solid though I still hold a grudge against him for missing a game-winning kick against Virginia in 2014. I think having really good special teams might have helped my teams overperform a bit both years as I easily won the field position for a couple of years until they graduated in '17 and '18.
I ended up getting a 4/4 redshirt freshman punter to replace Singleton and he's been solid in both of his starting years. I have a 3.5 power-player at kicker, but he went 30/31 last year with multiple 50+ kicked so I think that's pretty good. IIRC, he hasn't missed a field goal this year either. So I guess you can have success with lower-rated players theoretically (they just have to be the right ones). Hell the best college RB I've had so far is a 3/3.
In the pros, we had really terrible punting in our first year. And our second year. (Our punter, Dennis Carson, had something like a 37 average in 2015). In the 2016 draft, my biggest goal was to fix the QB position (sorry loltar) but my second biggest goal was to fix special teams. We ended up taking John Maslowski (#LEGZILLA) in the 5th round and he's pretty much solidified the punter position for us, turning it from one of the worst units in the league to a top-5 one every year until this year. He even made his first Pro Bowl last year!
At kicker we had Ken Hodel in 2014 and 2015. I think he was a 3.5/3.5 coming into the pros but that was acceptable back then and he did make 83.3% of his field goals in his first two years. Unfortunately he was a power kicker who'd never made a field goal from 50+ so I figured it was time to move on. We ended up signing Paul Compton out of Boise State, and boy was he terrible. He was 11/18 in his one year as our kicker, and missed multiple game-winning field goals in a year where we went 10-6 (if my memory is correct). So I again resolved to fix the position in the draft, and we ended up taking Chris Hoag in the comp picks in the 3rd round. The panel on that draft trashed me for it a bit but that draft had terrible depth so I don't really regret it, though we maybe could have taken Gino Chiaverini instead. He did solidify our kicking position and has been solid, though missed XPs have been a slight problem. He made a game-winning kick in the 2018 divisional round against Miami to give us our first ever playoff win so I'll always have a soft spot in my heart for him for that. Still better than Paul freaking Compton.