Doing some quick math using the
League Averages page, it looks like 2B average about 5.75 chances per game, which over 162 games is 931.5 chances. So, Beckert, with a .968 FLD% works out to 29.8 errors (and you'll notice he averages 30 per season on his performance history). Clarke, with his .990 FLD% comes out at 9.3 errors (and 8 on his PH). Rose with his .959 FLD% works out to 38.2 errors (and he's barely been used at 2B on his PH, but his partial rate comes out to 32 errors there).
Now, also factor in +/- plays, (2/4, 3/1, & 0/3, respectively), and Beckert will cost you approximately 32 outs, Clarke 6, and Rose, 41. Offensively, using RC (and a typical progressive environment of ~6.5 runs per win) Beckert is worth approx 70 RC, Clarke 75, and Rose 106. Offensively, Rose is worth about 5 wins more than either of them, defensively, Beckert doesn't make that up at all defensively, while Clarke picks up about half the difference on defense. So, if Beckert is your option, then stick with Rose and draft an OF that will get you any value beyond Beckert. If Clarke is your option, I might take him, but this is only looking at one year. Long term, I like Beckert better than Clarke, but I'd prolly still take an OF and play Rose there than draft either of them and hope to get a better 2B option in future draft ('66-'68).