Looking for just ball park figures here, obviously there will be a lot of variation. Here are a few questions and a few guesses:
(1) How difficult is it to qualify for the US Open?
The answer obviously depends on the sectional tournament you’re in, but I’m guessing it’s quite a bit more difficult than making the cut at a PGA Tour event. It seems to take about -0.25 SG/round to make the cut in an average PGA Tour event; I’m guessing it takes closer to +1 - +1.5 SG/round to make it through sectionals. So a player like Jason Kokrak might be around 50-50 to make it.
I actually think it’s easier to get in through a smaller sectional than trying to get through the gauntlet in Ohio. But that’s something that bears further study.
(2) How difficult is it to get through Monday Qualifying?
Obviously not every qualifying is like the one for the Phoenix Open (which was basically a 18-hole Korn Ferry Tour tournament) where you probably needed like +3 SG to get in. But I’m guessing it’s still tougher than a Mini Tour event, so you’ll probably need a +1 SG on average.
(3) How tough is it to win a mini-tour event?
I’ve seen some of these fields. The winners are generally former college stars trying to make it to the PGA Tour. Field size is usually 15-30 and only half the players are competitive but you need to go low to win. My guess is 0 SG, though this will vary a lot.
(4) How competitive are the independent events?
There are quite a few 72-hole tournaments with purses ranging from 50-300K that are not part of any tour, like the Pebble Beach Invitational, Colorado State open, Long Beach Open, etc. Many of them are State Championships run by the state golf associations, and have a good list of sponsors. Given the purses, I’m actually surprised that they don’t attract a stronger field than they do. It’s not uncommon for PGA Tour players to participate in these types of events and they usually do not win. I’m guessing +1 SG/round will be pretty competitive, maybe about as tough to win as a Champions Tour event.
(5) How good are the top club pros?
Many top club pros are actually former (or current!) mini tour aces and some were (successful!) PGA Tour pros in the past. Many of them are top players in the independent events. I’m guessing that winning the PGA Club Pro Championship would be on par with winning the biggest independent events, so I’ll guess that +1 SG/round would have a decent chance.