From the Fangraphs blog about today's deals... regarding Evan Silva:
As for Detroit, the decision to trade Canha feels straightforward. They’ve fallen out of the playoff race, but they didn’t want to trade Tarik Skubal (rightfully so, in my opinion). That means the only thing left to do is send out players on expiring contracts and get whatever you can for them. Canha fits that bill, and he was never going to command a huge haul, so they took what they could and moved on.
Silva is an interesting prospect, though his value is capped thanks to a switch to the bullpen last year. He needed it; a high-effort delivery means he can touch the upper 90s despite a diminutive frame, but he struggled with strike throwing in A-ball. He’s a full-time reliever in Double-A this year, and while his walk rates still aren’t pretty, he’s striking out 30% of opponents to make up for it. He has good secondary stuff and is still only 21. He might be a whiff-reliant multi-inning reliever in the majors; he was logging two-inning stints fairly often for the Giants. He’s somewhere on the 35+/40 FV borderline.