I agree that the fridge won't be the problem. The air temperature may fluctuate, but the wine temperature won't. That's not a fault of your fridge; it's typical of how they work. If the fridge had to keep the air temperature at a steady 57 degrees, the compressor would be running constantly.
Since those are relatively recent vintages, could it be that they've simply shut down? They may have been lively and primary when you first tried them, but I wonder if they've now entered a dumb phase where they aren't showing much of anything. Perhaps you need to let them sit for a few more years.
But I haven't tried recent Silver Oak or Mondavi entry level bottlings, so this is a bit of a guess.