The 49ers are considered to be one of the very best teams in the NFL, but that doesn't mean that they don't have some important needs to fill after losing the Super Bowl. All too often we have seen a team go from conference champion, to Super Bowl loser, to out of the playoffs the very next year.

Does San Francisco need to worry about that? What can they do to help avoid a collapse?

For more on the 49ers, check out Niners Nation

One such problem that they ran into as a team last year was the significant loss of defensive lineman Justin Smith. Hurt in the middle of a game against the Patriots, Smith was out for the second half of that contest and the next week against the Seahawks, and the 49ers gave up 73 points in six quarters. That can't happen again and it would make sense for San Francisco to bulk up on the defensive line, especially after losing Ricky Jean-Francois to free agency.

With that being said, Rob Rang of CBS Sports projects DT Jesse Williams of Alabama to the 49ers with the 31st pick of the first round in his latest mock:

Justin Smith is expected to make a full recovery from the torn triceps which drastically limited his effectiveness late last season, but he'll be entering his 13th season in the NFL. The 49ers lack much depth behind him, something the Ravens exposed during their Super Bowl victory. Williams starred this past season at nose guard for the Crimson Tide but played outside at end in their 3-4 alignment in 2011. That versatility could certainly intrigue at this point in the draft.

Williams is one of the strongest prospects you'll ever see. Is he strong enough to replace "The Cowboy"?

More from SB Nation:

• Printable bracket for March Madness

• NFL Mock Draft: Geno Smith's rapid rise

• Bills aggressively scouting quarterbacks

• Tony Romo close to extension with Cowboys

• Tyler Eifert could be a first-round surprise

• Jake Long's impact on the Rams