I'm familiar with the idea, but typically when you make a trade of that nature you aren't giving up an actual prospect, it's more of an org guy that gets shipped out. Maybe Conine ends up being an org guy in a few years, but I don't think it was necessary to throw him away in a trade with a high risk of completely failing. One of the major weaknesses in the Jays minor league system is the lack of good outfield prospects, sending out one of the few interesting players they had for a month of a backup shortstop seemed short sighted.
If the front office thought Villar was a good fit for the club they could have had him for free at the waiver deadline the at the previous waiver deadline, they didn't need to give up an asset to acquire a month of a player having the worst season of his career up to that point. Reports out of Miami were that Marlins management was happy to be rid of Villar due to selfish play as he was making a lot of boneheaded forced mistakes on the field, and that continued after the trade. The Jays were working hard to clean up the unforced errors on the basepaths, and Villar came in and instantly started running into outs on the bases with reckless mistakes.