Where do offensive linemen come from?
The answer my parents gave me about a giant stork seemed pretty farfetched, so I dug through NFL.com and Pro-Football-Reference.com to get the real picture.
This past season 156 linemen started at least 9 games, 31 centers, 61 guards and 64 tackles (32 left, 32 right). Where were these starters drafted? Were they picked up in free agency? Is there a difference between the positions in where starting linemen are found?
By round the number of starters trended downwards as you moved back through the draft. 38 of the 156 starting linemen were first round picks, 30 were 2nd rounders. 18 starters were taken in the 3rd round, 16 in the 4th, 10 in the 5th and 9 starters each coming from the 6th and 7th rounds. 24 starting linemen went undrafted. Starting caliber linemen come from all over, but it appears that NFL front offices know what they are doing drafting linemen. The first 1/4th of the draft (rounds 1 and 2) account for over half of all drafted starters and 44% of all starters.
The premier position on the line, left tackle is dominated by high draft picks. Half of the league's starting left tackles last year were 1st round picks. 22 of 32 came from the top 2 rounds. The remaining figure of 10 LTs who weren't drafted by the end of the 2nd round is matched by the top 12 picks of the draft alone with 10. Just two starting LTs went undrafted, LTs are overwhelmingly found early in the draft.
Over on the other edge the same trend is present to a lesser degree. 1/4th of all starting RTs were 1st round picks and well over half (20/32) came out of the first 3 rounds. 4 starting RTs went undrafted.
On the interior draft position was even more evenly distributed. Centers tended to be a bit more highly drafted but only very slightly, 5 of 31 centers were 1st round picks against 9 out of 61 for guards and while only 4 of 31 starting centers weren't drafted, 14 of 61 starting guards went unpicked. The median overall pick was 92nd for centers vs 108th for guards. On the whole the first two rounds yielded 43% of the drafted starting G/C and a bit over 1/3rd of the total. While starting interior linemen still tended to be early picks, the trend is at it's weakest here.
Almost 3/4ths of the starting linemen around the league (114 of 156) have never played a game for a team other than their current one. As always, most of your talent needs to be homegrown in the NFL. Guards were by far the most likely to have suited up for another club in the past with 23 of 61, solidly over 1/3rd of starting guards on at least their second team. Centers checked in at a bit under 1/3rd, 9 of 31. RTs at 1/4th on the nose, 8 of 32. The real outlier are the left tackles. Just 3 of the 32 starting left tackles have ever played for another team, interestingly none of the 3 starting LTs to have played for another team were drafted in the first 4 rounds of the draft. Starting linemen do hit the open market regularly, with the glaring exception of left tackles.
Upcoming: "Where do GOOD starting linemen come from?"