i think brown, johnson, and verhaeghe have moderately higher offensive ceilings than leivo and gauthier, but leivo and gauthier have higher floors.
I like this analysis the best, although I never like to put a cap on players potential because they can always be better than anybody expects, I think its fair to say that the first three have a higher likelihood of being good offensive producers. If everything worked out good, I see these as suitable comparisons:
Brown seems like a hard working 2-way 2nd line winger, decent defense good offense for a 2nd line winger.
Verhaghe seems like a 2-way #2C with good hockey IQ and just knows where to be. Does the little things right and tries to keep his game fairly simple.
Johnson I can't comment on as I've almost never watched anything besides highlights.
Leivo is a north-south type player with decent hands and a nose for the net. Good forechecker, average? defense, good shot, and a good forechecker. I'm thinking 2nd line winger, could be below or above average #2 winger.
Gauthier seems likely to be a #3 C. I'm hoping he can become a Sutter type #3C (value wise, not playing style) with 30ish pts, great defense, great face offs, and hopefully uses his body to his advantage. Looking at his range id say McClement-Hanzal and I'm hoping for a B sutterish type player.