While that deck will certainly have pulled many copies of This Town Ain't Big Enough out of circulation, by itself it isn't the main reason for this spike
This will start generating tokens to act as attackers and blockers, with your commander handling the ability to set up the battlefield for both offense and defense
More mana income is good, but theres always the risk of overdoing it
Grist, the Hunger Tides first ability states, As long as Grist, the Hunger Tide isnt on the battlefield, its a 1/1 Insect creature in addition to its other types. This is a characteristic-defining ability that applies to Grist at all times
Various Ajani incarnations offer life, they are all fine but need to be played in the appropriate place to be good and in such places you are typically not doing so for any life based reasons
From what I understand, Manchester and Concord also have a 30-day hold, as do our neighbors in Lowell