Bergwijn arrived at PSV's academy from rivals Ajax in 2011, and made his professional debut in 2014-15 while playing for their youth/reserve side, Jong PSV in the Eerste Divisie, Netherlands' second-highest league tier. At Jong PSV he collected 27 appearances and 12 goals in the last two seasons.
The crux of the rumor appears to be that the Dutch youngster has recently joined Portuguese super-agent Jorge Mendes' stable of clients at Gestifute, and the close ties between the agent and Chelsea could drive Bergwijn towards a move to the club.
His highlight reel videos (far from the best scouting tool out there) show a predominantly right-footed left winger who does know how to use his left foot as well, and uses his pace and strength to impose himself on the pitch. He's often cutting inside and making runs from central positions, arriving at the box to finish off chances, and seems fond of trying long-ranged attempts at the goal. His technique seems rather unrefined at the moment, but he's still young and presumably has plenty of room left to improve.
In his current predicament, Bergwijn has "loan army" written bright and clear on his forehead. With Memphis Depay in the 2014-15 season and Jürgen Locadia in the last one dominating PSV's left wing, he hasn't had many chances to play in their first team and, if acquired, could really use a loan move to back to PSV or somewhere else — loaning him to Vitesse would seem like a trollish thing to do though — to develop and refine his game a bit further.