Speed and Defense: How Much The Detroit Tigers Added This Offseason

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May 2, 2013; Houston, TX, USA; Detroit Tigers first baseman Prince Fielder (28) slides into home safely against the Houston Astros in the eighth inning at Minute Maid Park. Mandatory Credit: Brett Davis-USA TODAY Sports

The Detroit Tigers offseason thus far, at least as far as the offense is concerned, has followed two general guiding principles: add speed and add defense. Or, at least, that’s how the narrative has gone.

Trade Prince Fielder for Ian Kinsler? Look at that athleticism upgrade. Move Miguel Cabrera from third base to first? They’re getting better at both positions. Sign Rajai Davis? He’s going to steal every base.

But was does the upgrade actually look like in terms of runs gained (by base running) and runs saved (on defense)?

That question is hard to answer because speed and defense are hard to measure. You need a large sample size to be able to rely on the numbers – it’s said that three years of defensive data equals the reliability of one year of hitting data – but once you have the requisite sample, you end up with a possibly different version of the player than you started with. But we can try, anyway.

What follows is a comparison between the Detroit Tigers team we saw in August and September and the Detroit Tigers team we expect to see in 2014. I’ll use three years of UZR (defense) data and BsR (base running) data, as reported by FanGraphs, for each applicable position below. When utilized, data is scaled to 600 PA or 1250 innings.