Hey, we're all free to possess our own opinions... However, I would suggest that if you believe Upton's failures during his tenure with the Dbacks is due to him being "mishandled", I would simply say you are dead wrong.
Further, Upton has never come close to 40 HR's - hitting over 20 only twice thus far in his career.
He's off to a nice start this season, however, in typical Upton fashion, his RBI total is sub-par given his HR total (5 HR's and only 7 RBI). He's never exceeded 90 RBI in a season. He has also been a strikeout machine during his career and, right on cue, he presently leads the majors in strikeouts - he's got 25 plate appearances thus far, and 11 strikeouts...
You may not agree, however, I can completely appreciate a team that prefers a guy like Prado with his career .295 average and with a strikeout rate a fraction of Upton's. Since '09, Prado has racked up hit totals of 138, 184, 143 and 186. Over that same time, Upton has 158, 135, 171 and 155, while literally striking out more than 2x the amount of Prado! And lastly, Prado can play multiple infield and outfield positions which only adds to his value... whereas Upton is a right-fielder, period.
I applaud the Dbacks for making this move...