The placental mammals are about 20 aa differences from each other, while carp is about 70 aa differences from any mammal. So, the divergence time of mammals should be approx. 3.5 times earlier than between the carp and mammal lineages. Rate variation within genes correlates with selective constraint. So, stabilizing selection must be much more important than positive selection.
Silent sites evolve faster than replacement sites.
We might need to explain the the difference between silent and replacement sites and degeneracy of the code and all that. Pseudogenes evolve fast. Once again, using the logic of above, this shows that stabilizing selection influeneces rates more than positive selection. This is why synonymous sites are evolving slower than pseudogene sites. Yet again, if increased evolution rate were due to positive selection, you'd think that synonymous sites would be evolving faster than pseudogene sites.