Pixelated Images

I just posted a blog that features a gallery and full width image. All of the images in this particular post are pixelated and blurry.

Not sure if this is relevant but the images were exported from adobe lightroom at 72 PPI
Initially I saved for web and that brings the quality down a bit so I exported again at high quality but still at 72 ppi. None of the other images on our website look like this and they have all been smushed. However, most of them were not saved for web so not sure if that is messing something up or not.

Images look reasonable on my iPhone 6+ but look awful on my iMac. I am not sure what is causing this to happen and I am looking for a solution to the problem. Here is a link to post: http://www.hinsonphotography.com/beach-portrait-session/