Why would LA trade their best young defensemen for fringe NHLers and a 4th?

LA might be inclined to do a POJ for Durzi swap, but even then Pittsburgh has to add.

Without even getting into a discussion about quality, we already have 13 forwards on the roster with Gabe Vilardi (who's no longer waivers-exempt) yet to sign and kids like Alex Turcotte and Jaret Anderson-Dolan in Ontario NHL-ready, so a bottom-6 forward like Drew O'Connor is just excess, and Friedman is certainly no improvement on Sean Durzi, so there's no reason for Los Angeles to make this exchange.