What is the opposite of "in name only"?

I want to describe a player who is not officially the captain of a team but shoulders as much responsibility. I have read the phrase in name only being used when a person holds a title, but doesn't perform or is unable to perform the duties typically associated with it. I would guess that in my case I am looking for a phrase which is opposite of in name only. The person is performing the duties but doesn't officially hold the title.

I searched for the opposite on Google but couldn't find one. Ended up with a similar result from a couple of dictionary searches as well.

The person is performing the duties but doesn't officially hold the title.

Jerry is the CEO in name only.

Csarina is effectively the CEO:

1.1 Actually but not officially or explicitly:

ODO

I think Scot's answer is perhaps more accurate, but for my exact sentence I ended up using:

in all but name

It applies to conditions as well and is not limited to describing a person. Source: http://idioms.thefreedictionary.com/in+all+but+name