If you look at my team:
http://boincstats.com/stats/boinc_team_graph.php?pr=bo&teamcpid=4da5bb4d5f9c3a1abca15d586b22d309
You'll see that on 2011-02-01 there was over 300k credits earned, a large chunk on Milkyway.
However if you look at the members, there's nobody with anywhere near that amount of credits (if you total them).

There used to be someone in my team that did a lot of credits for milkyway, then they vanished, I'm wondering if they are back but as a "ghost" or something.

In either case something is going on with milkyway and teams I think. I was on milkyway last week and it said I was in a team but there was no team name, and other weird glitches like that. I'm wondering if the data is corrupt somewhere?

Usually credits once granted to a team stay with the team, with the exception of the climate projects.

Yes, I understand that what they've earned stays.
I'm talking about recent credits.
As in, credits today based on t he incremental updates.
Or credits added yesterday.
This user seems to be contributing credits to the team still, however they do not show up on the members list.

If you add up the credits per day on the members list, it does not add up to the credits the team is generating per day....

I've found the user contributing to my team who does not appear in my team on boincstats:

http://milkyway.cs.rpi.edu/milkyway/team_members.php?teamid=2984&offset=0&sort_by=expavg_credit
That "GARP" person does not appear to be in my team on boincstats.

Yet the team gets credit from them (on boincstats).... any idea?

They don't show on your overall team list because they are in another team 'Canada' on SETI. Normally overall team membership at BOINCstats is based on the team you are the member of at the most projects. In this case with 1 and 1 some other logic kicked in and for overall membership they are listed at part of team 'Canada'.
See their full stats here, note they also seem to have a different username for SETI which also won for overall stats listing.
http://boincstats.com/stats/boinc_user_graph.php?pr=bo&id=07db0aae32f8d44378834b159b6620a2

If you look at your team MilkyWay stats you will see them as a member.
http://boincstats.com/stats/user_stats.php?pr=milkyway&st=0&ti=2984

Ahhh I understand now.
Thanks!