Jim Caldwell knows what he wants out of his team. Not in general terms, in specifics.

“The first words that I said in this town, offensive line and defensive line is the heartbeat of your team and they have to be able to control the line of scrimmage,’’ Caldwell said on Thursday.

“We knew what we wanted to look like. “I’ve been showing the team this from the first day that we started our regular season,’’ Caldwell said. “Hey this is what we need to look like, these are the numbers we need to see.’’

Obviously it worked in the regular season because he’s preparing the Detroit Lions for Sunday’s wild-card playoff game against the Cowboys at Dallas.

The veteran NFL coach, who has been to three Super Bowls, said there are three commonalties among postseason contenders.

1. The turnover ratio is plus-3 or higher for the playoff teams with the exception of three. The Lions were a plus-7 in the regular season. (They were minus-12 in 2013.)

2. The best teams excel at stopping the run. The Lions’ rush defense ranks No. 1 in the NFL. Of the top 10 rush defense teams, seven are in the playoffs. Dallas ranks eighth.

3. Running the ball is key even though not quite as black and white in the standings. “The running game has always been important, this time of year or whenever,’’ Caldwell said. “You also heard me say the last four or five weeks our running game has been different.’’

In last four games the Lions had 111 rushing yards against Green Bay last week, 111 against Bears on Dec. 21, 80 vs. Vikings and 113 vs. Buccaneers. 

“Those are the kind of numbers you’re looking for, you want to get over 100. So I think at the right time our offense is doing a better job in terms of the run game,’’ Caldwell said.