Good question, Reddick v. Kalish. Here are their minor league career numbers. Keep in mind that Kalish is one year younger.
Career minor league season stats
Reddick (5 seasons, 466 g): 1821 ab, 86 hr, 299 rbi, 35 sb, .278/.332/.500/.832
Kalish (7 seasons, 412 g): 1553 ab, 45 hr, 212 rbi, 95 sb, .282/.370/.436/.805
AVERAGE PER 162 G
Reddick: 633 ab, 30 hr, 104 rbi, 12 sb, .278/.332/.500/.832
Kalish: 611 ab, 18 hr, 83 rbi, 37 sb, .282/.370/.436/.805
I mean, both were good minor league players that offered the Sox a lot. Different emphases, really: Reddick with less speed and more power, more slugging and less OBP. Kalish just the opposite - more speed and less power, more OBP and less slugging.
Pretty similar in terms of fielding. Minor league fielding stats:
Reddick: .974 fld%, 2.18 RF/G, 62 assists
Kalish: .977 fld%, 2.22 FG/G, 25 assists
So Kalish a little better fielder, Reddick a better arm.
All in all, probably six of one, half-dozen of another. Plus, keep in mind this: when they made the Bailey trade, Kalish was hurt so Oakland didn't want him. They wanted a healthy player in return. So they couldn't have traded Kalish even if they had wanted to.