The trade makes sense to me. Arodys might have a future as a power reliever, but that’s an area the Cubs are flush with. The Cubs are also flush with middle infielders, but you’re deluding yourself if you think the Cubs’ brain trust considers La Stella anything more than the first backup out of Iowa. La Stella has options, so the clear play is to option Tommy to Iowa, outright Logan Watkins from the 40-man (bringing it 37), and trying to sneak him through waivers (which he could clear, as we are at that time in the offseason when teams are making their Rule 5 protections and husbanding their 40-man spots).
La Stella is the polar opposite of Javier Baez. Javier Baez strikes out a ton; La Stella hardly ever strikes out (10.5%). Javier Baez never walks; Tommy La Stella walks a ton (10%). Javier Baez is athletic and a potential weapon at SS or 2B; La Stella can barely play 2B and is a liability anywhere else. Javier Baez might hit 40 HR in a season; La Stella might hit 4. Javier Baez is one of the top prospects in the whole game; Tommy La Stella isn’t.
I’m slightly disappointed that the return for Arodys is so low, but I imagine the Cubs really just value the 40-man spot (that they get from out-righting Watkins) more than the fringey upgrade they might get if they traded for someone else. Still, it’s hard to be mad; this trade has almost no effect either way at the MLB level, and is unlikely to ever really matter. With trades like this, you almost just have to defer to the front office’s valuation of the assets.