The 49ers haven't been together en masse since the end of the 2010 season, but they are expected to have good numbers today when quarterback Alex Smith holds the first of several 'Playbook 101' sessions with the offensive players. Familiarizing themselves with Jim Harbaugh's playbook will be key to a good start to the regular season, and in that way alone these player-led sessions have value.
* Three 49ers quarterbacks will be on hand: Smith, David Carr and rookie Colin Kaepernick, who is not yet ready for full practices. The question is, how many receivers will show up? The big mystery is presumptive No. 1 receiver Michael Crabtree, who has been in the Bay Area the last few weeks but who has not worked out with Smith and the group of receivers who work out together. Josh Morgan, Kevin Jurovich, Ted Ginn, Kyle Williams and even rookie Ronald Johnson have spent some time working with Smith this offseason. Crabtree has not.
* Dominique Zeigler is expected to attend the week's session, but it is not known how much he will be able to participate. Zeigler suffered an ACL tear last season and is still recovering. Center Eric Heitmann is not expected to take part as he continues to recover from a neck injury that sidelined him last season.
* One prominent free agent, Smith, will run the session, but another, center David Baas, is not expected to attend. Another center, Tony Wragge, also is a free agent. When the 49ers offense lines up in team formations, Adam Snyder, could be the one taking the snaps.
* The 49ers, however, should have enough offensive linemen overall. Rookies Daniel Kilgore and Mike Person will be on hand. As will Joe Staley, Snyder, Mike Iupati and Anthony Davis. The other rookies who will take part are Kaepernick, running back Kendall Hunter and wide receiver Johnson.
I'll be tweeting throughout the week. You can follow me at @mattbarrows.
-- Matt Barrows