@royals119 is correct. The Toronto/Growlers situation is relatively unique because of Dubas' and the Big Club's philosophy. The Growlers are going to be stocked by AHL contracts from the Marlies and relatively few players contracted to the Growlers themselves. The ECHL has a strict salary cap, as such, an ECHL contracted player at most makes ~$30,000 per year (paid weekly) plus per diem and living expenses. When an AHL contracted player is sent to the ECHL affiliate the ECHL team pays the the AHL team his ECHL salary limit and the AHL team pays the rest. So,
in theory, you could have a player making $1 million playing in the ECHL, but that ECHL team only pays the ~$30,000 cap amount.
So, what Dubas is doing is finding a bunch of players who the organization thinks have potential, sign them to AHL contracts (where there is no salary cap) and develop them with the Growlers if they cannot make the Marlies.
So, the players that you noticed the Growlers sign are indeed local Newfoundland boys for marketing purposes, who are good enough to play in the ECHL (or potentially higher), but want to play at home, and the Marlies do not quite have them high enough on their radar to offer AHL contracts (at least not yet).
Last year, Dubas sent 12 players to the Solar Bears over the year who were under Marlie AHL contracts. This was a lot. The next closest were the Islanders system who sent 8 AHL players and 1 NHL player (who Ironically Dubas traded for in the Martin trade and will be on the Growlers this year - McAdam) to the ECHL Railers. However, this year, expect that 12 number to increase with the Growlers. I expect as many as 16-18 players under AHL/NHL contracts to play on the Rock at some point this year.
It's the development philosophy of the Leafs at work. Not too many franchises leverage their ECHL affiliate as much as the Leafs do. Some clubs don't have ECHL affiliates and will send their guys wherever. Most other clubs will send only a few to the ECHL; they simply don't have the budget the Marlies have to over-sign, as such don't have a lot of extra players. These clubs will call-up ECHL players from all sorts of clubs for PTOs whenever they need help filling out the roster. The Marlies must lose a lot of money every year -- a loss leader at the cost of developing players and trying to find hidden talents.