He's probably going to be projected to be a .360-.370 wOBA type bat.
So assuming he played 600 PAs in CF, he'd be roughly +26 runs above average offensively versus a generic league average bat, he'd get +2.5 for doing it in center, and he'd get an additional +20 for the difference between replacement and "average".
So the Reds would be looking at getting a 3.5-4.0 WAR player if they traded for Choo and stuck him in center and he played without significant injury.
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