First, there is no good statistic for rating defense other then scouting. Player 1 on the visiting team makes a diving stop past second base and throws out a fast runner by an eyelash at first, then makes a diving stop at a line drive tailing away, then has a ball hit a rock on a play he was perfectly positioned for that goes over his head for a hit. Player two for the home team has an easy grounder from a slow pitcher and barely throws him out. He boots a ball to his right but the official scorer is generous and awards a hit. He catches a popup. Statistically they are equal players. But scouting tells you otherwise. Zone ratings and runs against average are nice, but they don’t tell the whole story. Defensively, Neifi blows Todd away. What do you think Walker would do defensively over the course of the season if he played shortstop? Perez should be a better defensive second baseman then shortstop. Walker is a below average defensive second baseman. It should also be noted that his teammates, bosses, or anyone else in baseball is defending Walker’s defense. So it’s just a question of what is the net difference. Let’s put things in perspective. Assuming a 24 week season, 144 game, 500 plate appearance season for each; the difference between their career obp is .047 which amounts to 23.5 hits/walks over the course of a season or one base a week. If you assume 4 or 5 chances a game, and 1 to 2 hits getting through the right side of the infield a game; that’s somewhere in the area 720 to 1008 plays over 144 games. Defensively I think it would be fair (if not conservative) to say that Neifi would likely get to 6 more balls and convert them to outs, make 6 less errors, turn 6 more double plays, and not misplay 6 balls that aren’t ruled errors; or about 1 out a week. Given these are on balls in play giving up outs versus what is more likely to be a walk; I see it as pretty much a wash (or a slight edge to Neifi) comparing defense vs. obp The difference in slugging of .061 is what swings things back to Walker with an extra 30.5 total bases a bit unless you believe he will misplay 2 balls a week So the real question is how many less outs will Todd convert in a week then Neifi.