Aaron Donald just got a $40 MILLION raise from the Rams ... but he still might be underpaid -- so says NFL legend Bruce Smith.
The former Buffalo Bills pass-rusher explained his opinion to TMZ Sports just one day after Donald re-worked his contract with the Rams ... saying AD is so good, he could have asked for, and legitimately received, far more cash than he got.
"Aaron Donald deserves that and more," Smith said of the new, 3-year, $95 million contract Donald now has with the Rams.