Per clock per core, a Ryzen is within 5-7% of Sandy/Ivy era I'm gaming. So a stock 3570 and stock Ryzen 1300 would be so close it'd be pretty tough to tell the difference. But all cores at 4.8Ghz gives one hell of a boost to 3570k, compared to 3.5/3.9T, probably close to 20% overall, and at least 15%.
With less threaded games, tbh there isn't much of anything that can really surpass that approximate range, even my 5.2 8086k/3733 build probably isn't all that much better.
For newer titles that can use beyond 4 threads, a decent 4.2ish running 1600x or better would be what you'd want to get, so you'd be able to at least equal, and in many cases dominate the older pure no-HT quad core setups.