Matt Ryan says he's devastated over the death of his former coach, Greg Knapp ... writing in an emotional note Friday that the guy was "one of the most positive, consistent, and caring coaches I have ever been around."
Knapp -- who tragically died Thursday from injuries he suffered in a horrific bike crash in California last weekend -- was Ryan's QB coach in Atlanta from 2018 through 2020 ... and he clearly had a huge impact on the Falcons star.
"He made it a point to know our families and for us to know his," Ryan said on his social media page.