If one were to downgrade the Greyjoy knight, I think Stark’s should be as well. It doesn’t make them more vulnerable to Baratheon, since they have to win the sea battle before they can send any troops north. But it slows down Stark’s growth just a bit to match the lessened threat of being rushed by Greyjoy. I don’t think anyone has real balancing concerns as between Stark and Greyjoy.
As for Tyrell, they are clearly the weakest and begin entirely at the mercy of Westeros cards in a way that even Lanni isn’t. Still, I do think even a little buff can have a huge impact when it comes to starting positions. An extra fort for Margaery would be a less drastic change than a ship, while still changing the dynamics - a turn 2 rush from Martell could still conquer the sea and open up Tyrell’s home territory, but it would not also wipe out his entire sea strength in the process.
What I think you also have to take into account is that the goal should not be to create a total stalemate in the opening rounds. In addition to making for more boring, inert games, this actually would have the effect of unbalancing in favor of Tyrell. They have better lands in which to grow and consolidate, which makes them a greater endgame threat. Part of the dynamic is that Martell should feel pressure to extend themselves early on to stop their rivals from Growing Strong.
As for Tyrell, they are clearly the weakest and begin entirely at the mercy of Westeros cards in a way that even Lanni isn’t. Still, I do think even a little buff can have a huge impact when it comes to starting positions. An extra fort for Margaery would be a less drastic change than a ship, while still changing the dynamics - a turn 2 rush from Martell could still conquer the sea and open up Tyrell’s home territory, but it would not also wipe out his entire sea strength in the process.
What I think you also have to take into account is that the goal should not be to create a total stalemate in the opening rounds. In addition to making for more boring, inert games, this actually would have the effect of unbalancing in favor of Tyrell. They have better lands in which to grow and consolidate, which makes them a greater endgame threat. Part of the dynamic is that Martell should feel pressure to extend themselves early on to stop their rivals from Growing Strong.