Will,
Oak is very likely to check, the bigger timber the wider checks and 16" post is pretty massive one. I've seen splits over 1.5" wide so you could fit your hand in. Over time the check will progress and you'll see more of them all over the posts and beams. Those shall be located on sides close to the centre line.
Bending strap as you described is fine, but might not be necessary. Take a closer look at post/beam joint to see what happened to bearing face. Was housing deep enough to allow for movement? I presume housing should be at least 2" deep for this size of oak post and loaded beam.
I'm afraid we need to see some pictures to provide proper advice in this particular case. Can you upload some?
Michal
TFDesign.cz