On other surfaces, I'd agree with you but on grass, Berretini is comfortably the second best player around currently. He's been doing very well since last year and took Novak to 4 sets in the final as well. His BH does fail vs Rafa on other surfaces but I think on grass, it's something he'd be able to protect better. Cilic probably wouldn't beat Rafa but he'd have been a huge test as a R4 opponent especially given that he'd just gotten back into form at RG as well. The guy is a confidence player and he'd have been in the mood and he does like grass.
Honestly, there's no recent history of shocks because Rafa hasn't really played here in 3 years so there's been lesser chances. He's definitely improved since those 2012-2016 years when he was supremely vulnerable to a shock result here but this is still the only surface where you'd not be completely surprised if a big serving big hitter knocked him out.