I feel obligated to make one small nitpick: On the field, by major league standards, Berg wasn't that "supremely talented", as stated in the review. One has to point out the context that any viable big leaguer is still among the absolute best players in the world, but by those standards, his stats really aren't that good.
From the absolute basics (.243 batting average in a hitters era), to the somewhat more advanced (49 OPS+, which meant he was, in rough terms, about half as good as the league average in getting on base and hitting for power), to the very advanced (a career negative wins above replacement), they show a below-average player. Baseball Reference's closest modern equivalent to Berg on the field is Jorge Fabregas , another catcher who hung around despite mediocre stats. The author's own father, a rare concrete example of the "replacement-level player" (look at his rating), outdoes Berg in most categories.
That being said, he was good enough to play in the big leagues and his biography makes him a perfect character for alternate history, especially softer AH like this story.
I learn about Moe Berg in an article on a comics blog, where the blogger went in very well-though-out detail of how they'd handle hypothetically being given Doctor Strange. While of course, we still haven't been graced with a story where Moe Berg's a former disciple of The Ancient One, I'm glad someone's given one of history's most interesting characters his own adventure series.