How I do I aggregate or perform calculations on a time datatype in "MM:SS:MS" in MySQL?

I'm currently working on an NBA project and I need to take the average minutes played per player, but I have no idea how to aggregate or calculate the time datatype. I know you have to convert it, but I have no idea what to covert it to. For example: a value is 31:56:00, but when I use calculations on it, it becomes 315600 as an integer, instead of remaining as that datatype with minutes, seconds, milliseconds. I apologize if this has been answered, but I can't find any solutions online and I'm still learning the fundamentals of MySQL. Edit: Here's a screenshot of the data and I'll show what happens if I perform a calculation or an aggregate, it'll basically remove the colons and keep it as an integer, but I want it to remain in the same format.