The phrase "a guy capable of" is correct and usable in written English.
It can be used to describe someone's abilities or potential in a specific context.
Example: "He is a guy capable of achieving great things if he puts his mind to it."
Alternatives: "a person who can" or "someone able to".
"He's a guy capable of big things," Creighton Coach Bret Simon said.
"If we have a guy capable of winning this race it's going to be him and not me".
Tipsarevic has always been a guy capable of beating the best one week, and losing to someone ranked well below him the next.
The new manager, expected to be appointed in June, has to be a guy capable of going the distance, who will also need to be guaranteed the necessary time to leave his mark.
Almost certainly a guy capable of scoring a roomier spot had he asked, Chance seemed to understand that he'd want to be front and center for whatever Beyoncé had in store.
He's a suit with the soul of a fan, a white guy capable of hearing an unknown African-American bluesman, Lester Grimes, and sensing raw brilliance that no one else gets.
"What his parishioners say is all true — he is a great guy, capable of great things".
This seems to hint that maybe Rhaegar wasn't such an awful guy capable of rape and kidnapping after all and that maybe he and Lyanna were actually in love when (and if) they conceived Jon Snow, as Zap2It points out.
The difference is now they're also good enough, with a No. 2 guy capable of being a No. 2 guy, a No. 3 guy capable of being a No. 3 and so on down the line.
An instructor from a prisoner art program once described him as "a promising beginner" and "a very talented and very meticulous guy, capable of a very high concentration".
The sort of guy capable of drumming up a ripe nostalgia for the present.
