Offensive line is a strength shared by the four conference finalists. Here’s a look at how the Chiefs, Patriots, Saints and Rams acquired their 20 starting linemen:

At a glance

Drafted 10

Free agency 4

Trades 3

Waiver wire 1

Street free agent 1

Rookie free agent 1

Average age 27.6

Under 30 Chiefs 5; Saints 4;

Patriots 4; Rams 2

Drafted by round

First 4 (3 by current team)

Second 6 (3 by current team)

Third 3 (2 by current team)

Fourth 1 (1 by current team)

Fifth 1 (1 by current team)

Sixth 1 (0 by current team)

Seventh 2 (0 by current team)

Undrafted 2 (1 by current team)

A closer look at the …

Rams: Despite having the two oldest linemen — 2017 unrestricted free-agent signings Andrew Whitworth, 37, and former Vikings center John Sullivan, 33 — they have the only fivesome that didn’t miss a start in 17 games. Spent second-round picks on LG Rodger Saffold (2010) and RT Rob Havenstein (2015).

Saints: All five starters were drafted in the top three rounds, three by the Saints, including first-rounders LG Andrus Peat (2015) and RT Ryan Ramczyk (2017). The only starter older than 27 is center Max Unger, 32.

Chiefs: They start former first- and second-round picks of the Browns in LG Cameron Erving (trade) and RT Mitchell Schwartz (free agency), respectively. LT Eric Fisher was drafted No. 1 overall in 2013. RG Andrew Wylie went undrafted in 2017 and was on three practice squads, including five weeks in Cleveland, before being signed off the street late last season. He became a starter in Week 7 this season.

Patriots: The only finalist without a starter picked in the top two rounds. RT Trent Brown, a 49ers seventh-round pick in 2015, arrived in a draft-day trade last spring. LG Joe Thuney (third round), RG Shaq Mason (fourth), RT Marcus Cannon (fifth) and center David Andrew (undrafted) began their careers as Patriots. Cannon, 30, is the only starter older than 26.MARK CRAIG