It is what it is. Robertson wasn't great, nor as good as he'd been in Chicago, but the Phillies still might not make the playoffs or get to the World Series that year without his contribution. Ideally, any time one team trades short-term for long-term, both sides win.
If Brown ends up having a better career than Abel or McGarry that would sting at little but at the time of the trade he wasn't anywhere near their value.