Then they have to draft a running back, perhaps as high as the second round.
Next, they need to straighten out their offensive line.
Finally, they should give Jonathan Dwyer and Isaac Redman a chance to hang on to their roster spots. They can be part of an improved running game.
If the Steelers don't check off at least the first three points of this four-point plan, their ground game won't get much better in 2013. The Steelers were tied for 28th in yards per attempt with 3.7 in 2012.
Let's start with Mendenhall, who is an unrestricted free agent.
The decision to let Mendenhall go should have been made when he failed to report to Heinz Field after being inactivated for a game against the Chargers.
The Steelers need to rid themselves of the toxins from an 8-8, non-playoff season. Having one less player who puts himself ahead of the team is a good place to start.
Mendenhall's performance in his five-year career hasn't been good enough for the Steelers to tolerate that behavior.
He's averaged 4.1 yards per rush, but take away a 68-yard run in 2011 and a 50-yard run in 2010, and he's averaged less than 3.8 yards per rush in both seasons.
Mendenhall was suspended one week for not showing up at the stadium for that Dec. 9 game. When asked about the incident, he told the Pittsburgh Post-Gazette, "There's a lot of thought that goes into everything that I do."
That might be his problem. He thinks too much, and it shows on the field when he tries to get too fancy hitting holes. He tries to use too much of his brain in a game that requires brawn.
As Crash Davis said in Bull Durham, "Don't think; it can only hurt the ballclub."
As much as Mendenhall hurt the ballclub on and off the field, his speed will need to be replaced, which is why the Steelers must use a high draft pick on a running back.
Lacy rose to the occasion in the SEC Championship Game and the BCS title game. He ran for 181 yards against Georgia and 140 yards against Notre Dame. For the season, Lacy rushed for 1,322 yards (6.5 yards a carry) and 17 touchdowns.
NFL Draft Scout ranks Lacy as the top running back in the draft. He might not be worth the No. 17 pick that the Steelers have in the first round, but he could be gone by the time the Steelers draft in the second round.
The Steelers could trade down in the first round, use that pick on Lacy and get an extra second-round pick. If they don't get Lacy, Wisconsin's Montee Ball or Oklahoma State's Joseph Randle are likely to be available in the second or third round. Both could start right away for the Steelers.
Since drafting Mendenhall in the first round in 2008, the Steelers haven't taken a running back before the fifth round. They need to do that this year and give whomever they draft every opportunity to start ahead of Dwyer and Redman.
Dwyer led the Steelers with 623 rushing yards in 2012, the fewest yards for a Steelers leading rusher since Merril Hoge in 1991, according to the Pittsburgh Post-Gazette.
That doesn't mean the Steelers need to get rid of Dwyer and Redman. Both are restricted free agents whom the Steelers likely can keep by signing to $1.386 million tenders.
Chris Rainey's impending departure might increase Baron Batch's chances of staying on the team next season, but Batch will have to fight for a roster spot.
Dwyer and Redman could compete with a high draft pick for the starting job if the Steelers stabilize their offensive line.
Offensive line coach Sean Kugler left to become the head coach at UTEP, according to CBS Sports. During the hiring process for a new coach, one of the questions should be if he knows how to keep offensive linemen healthy.
Continuity matters on an offensive line, and the Steelers have to mix and match their offensive line every year because of injuries.
Only Maurkice Pouncey and Flozell Adams started every regular-season game in 2010, and Pouncey missed the Super Bowl and most of the AFC Championship Game after he went down with an injury.
No offensive lineman started all 16 games for the Steelers in 2011. Only Max Starks and Ramon Foster started every game in 2012. Marcus Gilbert missed the final 11 games, and Willie Colon missed the last five games. Mike Adams, who took over for Gilbert, got hurt against the Browns and sat out the last five games.
The Steelers had three 100-yard rushing games in 2012: two by Dwyer, one by Redman. They came on three consecutive weeks when the only change on the line was Doug Legursky starting one game at center in place of Pouncey.
The Steelers won all three of those games.
An improved ground attack starts with five players on the offensive line who are used to working with each other. That won't happen unless the Steelers reduce their injuries on the offensive line.
If they can do that, Steelers running backs might not have to think so much about which holes to hit, and we know what Crash Davis says about thinking.