I’m not sure why, since they are already loaded at this position. They are probably preparing to trade one of their two catchers, Derek Norris or Austin Hedges.
The Padres also signed former major league pitcher Phil Humber, whose claim to fame is that he pitched a perfect game back in 2010. Aside from that, he was terrible, and so has spent the last few years in Japan.
They also acquired four Rule V draftees (see earlier story).
In short, not much happened today: a trade that is just a preface to another, bigger trade, a few Rule V draftees (most of whom will be sent back to their previous teams, and a minor league deal.
I’m sure there is lots happening below the surface, however. The biggest one: who is going to be the Padres next shortstop.