Keeping track of a team's dynamic roster gain/loss throughout the offseason is one of the keys to understanding their draft day moves and choices.  Enter Monitoring Team Needs, an at-a-glance way of checking up on your team's latest roster flux, as we count down through Free Agency, and into the days before the 2009 Draft.

Below is a table that breaks down this roster flux, showing who has come and gone, as well as updating the neediest areas of the team and some of the top names that have a good chance of being available when they pick in the Draft.  Draft prospects are linked to their Mocking the Draft Profiles and any names or positions highlighted in bold should be considered either to be positions of particular need and emphasis, or players of particular relevance and interest to the team's situation.  Below the chart we will discuss some of the names and situations described, and as always, you can join in on the discussion in the comments.

See you below the fold!

• LB Takeo Spikes was the second leading tackler on the team, with 122, and every indication is that he wants to be back.  If rumors of a 2-3 year offer are true, the 49ers will find it hard to turn down his pricetag, since it won't have a long term impact on the team's rebuilding efforts.
• WR Bryant Johnson won't be back.  With youngster Josh Morgan ready to step in the Niners will be happy to save money here.  At a certain point you should only pay so much for 45 catches, 546 yards.  There is some very good midlevel depth at WR this year in the draft, so with any luck the Niners can nab Hakeem Nicks, North Carolina, or Percy Harvin, Florida.
• In the backfield the Niners have a twofold concern, both involving RB Frank Gore to some degree.  Perhaps the most important is clearing out some actual lanes for him, and a reliable FB would be a great first step in this direction (along with strongside tackle).  They will have a chance to retain FB Zak Keasey, who missed some time with a biceps injury, but there are numerous options available in free agency as well.  Justin Griffith in Oakland, or Moran Norris in Detroit would be good choices.  Earlier there was word that Tony Richardson would be interested in blocking for Gore, but the Jets look to be committed to resigning Richardson.  The second concern for Gore will be picking up another big set of wheels to pair with him and help take some of the wear off, before the miles become too much.  RB Deshaun Foster showed he is still an effective back, but he will likely be allowed to leave after languishing on the bench most of the year.  This is another position that will almost surely be addressed in the mid-rounds of the draft, but the kind of product they are looking for may not be available after the fourth round.  Rashad Jennings, Liberty, and Arian Foster, Tennessee are both bigger guys who may still be around in the middle of the fourth, so some urgency should be involved with the pick.
• The Niners expect to have between $25 and $30 million in available cap space, but there have already been warnings that they are not interested in breaking the bank for any high-profile players.  Besides trying to resign many of their own guys they should be looking at some critical extensions for studs like LB Patrick Willis and pass rusher Parys Haralson.