A lot of different ways to do it, but it really depends on the sport. That advice may work well, but it may not be the absolute best.
So depending on the sport, here are a few general ways that it can be done (and then we can get into baseball specifics):
Feed the basal - you have a certain amount of basal running that may drop you low, but you are able to take frequent small amounts of carbs. This is good because the carbs provide energy. This is something that can be used for a long bike ride or run, as long as you have carb access. But you need the discipline to make sure you keep taking the carbs throughout the activity.
Fuel the activity - you take small amounts of insulin at specific times, and then take fuel for that. This is more for things where you NEED fuel, like 2 hours runs, and can’t rely on muscle glycogen alone. The problem with it is making sure the insulin you take matches the fuel amount.
BG prediction - starting with low IOB and low enough basal and high enough BG to make sure you don’t drop. This is for times when you can’t fuel and take insulin. This is what Daisy Mae is doing because it’s hard to take fuel and insulin while swimming! This is kind of what your CDE is suggesting
But…for baseball, there are several advantages you have. The dugout time gives you an opportunity to correct. Many times during a game. The downside is that they may not be predictable - if the other team is shelling your pitcher or the other team’s pitcher is shutting you down, you may not have a lot of time in your dugout compared to field time.
Another possible advantage in baseball is the ability to take carbs on the field. Catcher right? How much access would he have to a Gatorade bottle? Or some small candy in his pocket? As much gum chewing as baseball players do, seems like getting carbs throughout the game is not too difficult, right?
Here is where the feed the basal approach may be useful for baseball. As long as you have reasonable access to carbs, they can be taken as needed. Some games will be more intense, will need more. Other games will require less. But feeding what you need is easy.
If you can take carbs reasonably well, within a reasonably predictable time, you can manage this way.
I would encourage every dugout break to include a BG test, as long as he is not needing to head directly to bat. And dugout breaks give him a Gatorade opportunity. Also, I can set you up with some easy testing tools for that.
Don’t view it as managing 2-3 hours. Just manage it by innings. Always try to stay level until the next inning break. Even an occasional walk to the mound for a pitcher “conference” could be an opportunity to take a piece of candy if needed.
.