Low entry angle on many multi-valve production engines is intentional. It is one method to improve burn rate and reduce emissions. An engine with high flowing ports and a relatively quiescent charge motion in the chamber may not run as well as a head with a higher burn rate but less Vol eff.
I saw this first hand with a prominent NASCAR team owner who once personally took a head from one of his cars that was not running up to his expectations, took it to the flow lab, masaged it until it flowed like a mother - and made less power - because the burn characteristics were diminished. No names here
