If you're making changes to player.mdl for something like this, it's best to save the modified version as a new file.
Now, when translating the model in Blender, did you apply All Transformations afterwards?
It should be noted it's not necessary to even open the model in Blender at all. With a model viewer like
HLAM you can apply transformations directly to the model without any decompilation.
An alternative is to just decompile the model and add the
$origin 0 0 -36
option in the .qc file.