The phrase "a completely different guy" is correct and usable in written English.
It can be used to describe someone who is entirely unlike another person in terms of personality, behavior, or characteristics.
Example: "After spending time with him, I realized he was a completely different guy than I had imagined."
Alternatives: "a totally different person" or "an entirely different individual".
"He was a completely different guy after he talked to Roy Halladay in regards to his mental approach," Collins said.
He had retired once before, missing the 1995 season, and when he came back, Sutcliffe said, he was "just a completely different guy".
When the jolly veneer slips a little, on Saviour, he can pull off a few minutes of atmospheric intensity that seem like the work of a completely different guy.
"It makes no sense for us to roll out the red carpet for Trump when there is going to be a completely different guy in the White House in a month," Hendrik van der Valde, a travel minister for the Belgian government, said.
Is the tiger-blood-infused warlock now "a completely different guy"?
Afterward I'm still not sure how I feel about him, but I am positive that he is a completely different guy from the one who is written about in accusatory magazine and newspaper articles either that or he is very bored and very talented at adopting different personae and getting people to write about them.
Whitman was unabashedly enthusiastic about the development for her character: "People who knew Amber when she was sixteen or seventeen, there were a lot of different guys and a lot of darkness and a lot of confusion and always the same sort of guy, and then right when she started to get on track with her own life, all of a sudden out of nowhere comes this completely different guy," she noted.
Phillips said fellow graduates of the class of 2009 at John Horn High School were "just kind of flabbergasted, you know, just knowing that we walked the halls with him and talked to him and had classes with him and knew this completely different guy than what happened and what we saw on Thursday".
"I think they did a bit of soul searching and in pre-season the guys came back a completely different bunch of guys; all thinking alike, working for each other, working with each other, and as you can see we are reaping the rewards from that". Following his loan spell, Edwards signed a permanent deal with Millwall in the summer.
That's a completely different thing from a drunk guy in a kebab shop saying: "Hey Romesh, I love that show with you and your mum". That to me is like … fine, I can walk away from that.
"It's the same guy but a completely different set of circumstances," said actor Ron Perlman, who plays the patriarch.
