Thanks for the input. Cues that I might not be able to cancel MLB+ without paying for a full 12 months were 1) the description of the package on the website saying, "Monthly billing twelve months per year", and 2) when clicking Buy Now, the renewal terms on the next page saying, "renews with monthly billing twelve months per year". With both spots going out of their way to mention "twelve months per year", I'm cynically thinking you get locked in for 12 payments.
Free trial was a good idea, but apparently I'm not eligible. Maybe because I did a free trial 2 years ago before signing up initially. "You have already redeemed this offer. It will not be applied to the order."
Anyways, took the plunge on the monthly plan, will set a reminder for October and worry about cancelling then. Currently watching MLB Network on my smart TV, and all set to stream Brewers Radio Network tomorrow, so bring on the 2026 season!