As bad as Cleveland's OF has been, I'm surprised Cleveland didn't have this guy get at least a trial in MLB this year.
112 wRC+ in AAA doesn't mean much.
The outfielders that Cleveland has promoted from Columbus this year posted 215, 180, 165, 129, and 99 marks at that level (admittedly in some small samples). And the guy with the 99 wRC+ is 7 years younger than Barnes and possibly more capable in CF (and he had a 133 mark at AAA last year).
Actually, the outfielders Cleveland settled on haven't been that bad -- of their top 5 outfielders by PA, they've got Mercado with a 107 wRC+ in MLB this year, Naquin 105, Luplow 120. Compare that to the Twins, with Kepler 129, Rosario 110, Buxton 110, Gonzalez 91, and Cave 72.
Cleveland was really hurt by the leash they gave to Leonys Martin (61) and Jake Bauers (79), although to be fair Martin had a 103 in MLB last year with plus CF defense, and Bauers had a 95 as a MLB rookie last year and is only 23 years old, so they probably deserved some leash. Both Martin (released) and Bauers (optioned) are gone now.
Looking at Rochester outfielders, Jaylin Davis had a 173 wRC+, De Aza from the indy leagues has a 162 already, Cave 144... obviously not much room for them in the Twins outfield, but this puts Barnes's 112 in the same league in further context.