It seems like Benitez signed him for his ability to play out from the back, sweep and command his area whilst also being vocal in the back-line. He didn't play long under Benitez and spent most of his time at Newcastle playing under Steve Bruce.
Below are quotes which might suggest the type of profile Dubravka is.
THE Guardian: "I like to play as a right‑winger,” said the Slovakia international whose stunning display in his debut at home against Manchester United helped to consign them
to a 1-0 defeat. “Sometimes I play outfield in training and the coaches say: ‘Why are you a goalkeeper, maybe you could change to being a midfielder?’ But it’s too late – my father and grandfathers were keepers and I’m tall.”
Dubravka’s outstanding footwork represents a big reason why Benítez has transplanted this quintessential sweeper-keeper to Tyneside. “In modern football the keeper’s almost like a libero. You need to play with the ball, not just kick it long,” the 29-year-old said as he prepared for Saturday’s trip to
Bournemouth. “When I get possession the manager wants me to try to play football.”
"Nonetheless Benítez does not need a shrinking violet during a critical period when Islam Slimani, his loanee striker from Leicester, will miss at least three more games with a thigh injury. “He wants me to be loud and to talk to people, to help them and be confident on crosses,” Dubravka said." “I don’t want to look like I’m arrogant, just like I have enough confidence to help the guys. If I can see a striker three metres behind my defender, I’ll tell him. We need to know we’re all equal on the pitch. I don’t care if someone’s been here for five years, we have to fight together for the points.”
https://www.theguardian.com/football/2018/feb/23/martin-dubravka-goalkeeper-newcastle-bournemouth