your first image is slightly out of focus and both suffer from being degraded by a 2x TC. The 100-400 can be used nicely with a 2X tc, but I find the farther the camera to subject diatance the more degradation you get.
Get a STURDY TRIPOD and open up the lens one stop atleast. to shoot that etup ona monopod I would suggest 1/1000th and a sturdy tripod can get that image at even 1/60th if the GBH isn't moving.