They've lost 15 of their last 20 -- but the L.A. Dodgers should still be considered one of the FAVORITES when the playoffs roll around ... so says Bob Costas.

The legendary broadcaster was at LAX when we brought up the most depressing topic in Los Angeles ... how the once mighty Dodgers have fallen in a big way.

But Costas says despite the losing skid ... the Dodgers are still REAL contenders -- and he explains why in that signature Costas style.