This thriller is very well written and acted, with Rudd perfectly cast in the lead. But it takes at least one liberty with Berg's life that causes concern. (More on that below.) Even though he bears no resemblance to the actual, burly Berg, Rudd looks the part of a journeyman Major Leaguer of the time. And he has the depth to believably convey Berg's lively intellect and inner turmoil. When Berg learns just enough Japanese to prank his fellow players, when he surprises people with his ability in multiple languages, or when he accepts a difficult chess challenge on the fly, it all seems natural. Likewise, Rudd convincingly wrestles with the question of whether Berg should kill Heisenberg or let him live (a la The Hunt for Red October). The Catcher Was a Spy generates tension without a high body count or gruesome violence. But it's not Hitchcock-tight or thrilling; director Ben Lewin (The Sessions) wisely makes it more of an intriguing character study than getting into the nuts and bolts of spying.
In the supporting cast, Pearce is amusing as an American tough-guy soldier. Sienna Miller is sympathetic as Berg's neglected girlfriend, unsure whether he really loves her. And Hiroyuki Sanada, Daniels, and Giamatti are all memorable in supporting roles. The writing is a career best for Robert Rodat (Saving Private Ryan), who strips away sentimentality to highlight revealing moments. The dialogue is sharp, capturing the cadence of the time. In one exchange, Berg is asked, "You are a Jew?" He responds, "Jew-ish." But the presentation of Berg's closeted homosexuality is problematic, as it's apparently not based in fact. All biopics tweak and embroider facts, and, of course, it could be true. But presenting a big part of a real-life person's life as fact for dramatic motivation in a movie is a questionable practice. And, frankly, it's unnecessary: The real-life Berg is plenty fascinating.