I was bored, so I felt like doing a comparison of Upton and Miggy (pre-Tigers trade; Miggy was about the same age when his trade was made) and try to estimate if that would be an overpay for the Rangers. First off, let's look at what Cabrera did from his age 21-24 seasons (2nd through 5th years; first full season) compared to Uptons 21-24 (first 4 years where he didn't begin in minors).
Cabrera: 633 games, 20.8 WAR, .318/.405/.566, defense (while he flipped between COF and 3B) = not good
Upton: 580 games, 16.7 WAR, .285/.363/.485 defense = average with a UZR/150 at 2.0 and 16 DRS
Clearly Cabrera was the better hitter and Upton the superior defender, not that I needed to take all that time to figure it out. However I did to draw the comparison between the two. Cabrera was able to bring in two top 10 prospects from the year before they debuted (according to Baseball America). Upton wouldn't be worth that much, but Profar is the only Rangers prospect in the top 10 and, from all accounts, isn't going anywhere. A deal for a combination of Olt (who's currently blocked by Beltre although could play first) and Perez + organizational depth for Upton I would claim is fair. Olt is a top 25 prospect from what I've seen and Perez has been around 40-50 range despite his struggles. Let's not forget that pitching prospects are very unpredictable and if I were the Rangers and that was all it took I would be taking that deal today. Sure, Upton has health issues, but he's shown enough where having him for the next 3 years at what he's getting would be extremely valuable. Hamilton had his own problems as well and that's who Upton would be replacing.
Also it should be noted, Cabrera only had (I believe) one year left of arbitration before he would've become a FA when he was traded, while Upton still has 38.5 million over 3 years left on his deal. That averages out to a little less than 13 million a year. Considering a WAR win is about 5 to 6 million, he'd only need 3 WAR a season to make his deal profitable (which he has done 3 of the 4 years, with the other being worth 2.5 wins). Upton's clearly shown the potential to have big years (2011 gave him a top 5 MVP finish, 2009 was another huge year) and have the talent where he could potentially gain possibly 4 or even 5 wins a year. Say he gains 4.5 wins each of the next 3 years (on average). That'd be 13.5 wins, multiply that by 5.5 million (one WAR win) and Upton would realistically be worth almost 75 million. With simple math, 75-39 = 36 million dollars profit Upton would draw.