No one has to make any deal, did we HAVE to DFA Lugo? No ... but it was common sense. Common sense now tells you that by the time the Pads contend Gonzo will be in his mid 30s.
The Padres need to trade for high upside pitching. They should trade for as much pitching as they can, ala the Florida Marlins. What team has a surplus of young pitching, more than any team in the ML? The Red Sox ... and it just so happens we could use a corner infielder and an impact bat with Lowell's hip problems. Buchholz, Masterson, Lars, Reddick/Kalish ... offer that now.
The Padres won't have another winning team for AT LEAST 5 years, so it doesn't make sense to keep Gonzo on a team that won't win for half a decade. The longer you wait, the more his value goes down, and the less you would get in return because of the team's control over him and a contract extension.