It happens every year, a "raw" prospect that is widely known to be a great athlete, will test incredibly well at the combine in Indianapolis. A corner widely lauded for his speed will run 4.3, or a defensive end who's power and explosiveness leaves evaluators enamored will jump 11 feet, and suddenly stories will float that they are "flying up draft boards".
NFL players are by nature rare athletes, so when an individual stands out as the rarest of the rare, it draws even greater attention an notoriety. How many draft experts have you heard say something to the effect of:
Player X Is a wide receiver that wins with speed, consistently gets behind the defense, and adds an explosive element to his teams offense. Struggles to consistently catch the ball but can elevate to be in position to win contested balls. He has a high ceiling due to his speed and explosiveness. I gave him an early second round grade.
Then that player shows up in Indianapolis, steps on the field at Lucas Oil Stadium, runs sub-4.4 and jumps out of the gym, and suddenly you start seeing him show up in the middle of the first round in that same expert's mock draft, and move into the 20's in their player rankings. Has anything changed in that players' evaluation? Not really, he's the same fast and explosive player he was before the combine, but now he's higher on the board. Why? Because that evaluator is "Counting it Twice". He factored the athletic ability of the player into his initial evaluation and placed him high in the second round, mostly due to his physical traits, but now he's moving the player up because he ran fast and jumped high.
Josh Norris of Rotoworld, has talked about this phenomenon often over the last few years. Initially in his combine preview, all the way back in 2014.