I don't know about chess, but in the similar game Go, the very best centaur teams were at a similar or maybe even slightly higher level than engines until recen

I don't know about chess, but in the similar game Go, the very best centaur teams were at a similar or maybe even slightly higher level than engines until recently. This was due to cheese strategies, details of the rulesets and better extrapolation of intermediate results. However, this changed a few years ago, when engines learned many of the tricks that the human could contribute. Since then, I believe pure engines are stronger in all practical applications. Source: am national champion in centaur Go and worked on modern Go engines