WHEN THE DOLPHINS RUN THE BALL

You know about the Dolphins’ short-yardage struggles. They have converted only 12 of 26 tries on third-and-1 or less and only 5 of 11 tries on third-and-2. Well, Miami would be better off staying out of short-yardage situations because when opponents face third-and-3 or less, the 49ers defense has allowed just a 39.5 percent conversion rate. That ranks first in the NFL. Reggie Bush said he expects this to be the Dolphins’ most physical game of the season. If Miami cannot win the battle against San Francisco’s front seven, it basically cannot win the game because the 49ers aim to make their opponent a one-dimensional passing team and then come after the quarterback. The Dolphins don’t want that. Bush must keep his average around 4 yards per carry. And he needs to get enough carries to keep the 49ers honest. ADVANTAGE: San Francisco.

WHEN THE DOLPHINS PASS THE BALL

As good as the 49ers have been stopping the run, they have better credentials against the pass. They are ranked second in the NFL against the pass. Although the sacks are down slightly this season (the team ranks 10th in the NFL), the 49ers lead the NFL in sacks over the past three years. That is a big deal for the Dolphins this week because they will be without left tackle Jake Long to protect quarterback Ryan Tannehill’s blind side. Interestingly, the team is confident Long’s replacement, Jonathan Martin, can handle the assignment because he played left tackle at Stanford, played well last week in replacing Long, and is perhaps the future at the position. But the switch from right tackle for Martin forces Miami to move Nate Garner, the team’s sixth- or seventh-best lineman, into the starting lineup at right tackle. And that makes the chances of San Francisco moving NFL sack leader Aldon Smith over to Garner’s side highly likely. ADVANTAGE: San Francisco.

WHEN THE 49ERS RUN THE BALL

This should be epic. The thing the Dolphins do better than just about anything else on either offense or defense is stop the run. The front seven has been mostly consistent throughout the season. Only one running back has gone over 100 yards against the Dolphins and only three teams have gone over 100 yards rushing against Miami. But the thing the 49ers do best is — you guessed it — run the football. The 49ers are No. 2 in the NFL in rushing. Former Coral Gables High and University of Miami product Frank Gore has not slowed down in his eighth season. He is already the team’s all-time leading rusher and leads a rushing attack that averages 5.3 yards per attempt. The addition of Colin Kaepernick at quarterback also adds a dangerous dimension in that he can scramble as well as throw. ADVANTAGE: Even.

WHEN THE 49ERS PASS THE BALL

Randy Moss can still run and blow the top off the defense, but the 49ers have not been using him in that role very often. It’s the reason he has only 19 catches. Ted Ginn can run and blow the top off the defense. But he has caught only two passes and is mostly a return specialist. The big problems the 49ers pose are Michael Crabtree, a possession receiver, and tight end Vernon Davis, who has a knack for getting behind the secondary. Davis has catches of 53 and 46 yards this season and had a 100-yard game against the Bills. The Dolphins could be without Jimmy Wilson, their nickel cornerback, this week. That might not be a bad thing as Wilson has struggled in coverage this year. It he doesn’t play, that would mean either Nolan Carroll or R.J. Stanford would be coming on the cornerback blitz this week. ADVANTAGE: Even.

SPECIAL TEAMS

One special-teams flop against Buffalo was happenstance. Another against Seattle was a trend. And a couple of more miscues against New England are starting to look like a troubling habit. The Dolphins’ special teams are hurting the team’s chances of winning the past few weeks. That needs to stop. The 49ers aren’t having such issues. Punter Andy Lee is a three-time Pro Bowl player and kicker David Akers has been to six Pro Bowls. Akers kicked a 63-yard field goal against Green Bay in September — a kick that tied Tom Dempsey for the NFL’s longest ever. ADVANTAGE: San Francisco.

COACHING

The 49ers, at their core, are a very physical no-nonsense team. The problem they pose on offense is they take that philosophy and use disguise, misdirection and multiple sets that are hard to dissect or prepare for. Joe Philbin and his staff also have to figure out a way to make the loss of left tackle Jake Long seem inconsequential against, yes, the NFL’s sack leader. ADVANTAGE: San Francisco.