When fans discuss the Colts draft needs, they often start (and end) with interior offensive linemen. But the Colts draft needs at other positions seem far more important to me.

To most fans, the logic is simple: The Colts’ guards and centers did not play well last season, so they should be replaced with new guys. But it’s more complicated than that. Two very important factors stand in the way of the interior line as a primary need — the Colts are already better off than they were last year and the quality of guards and centers in the draft is less than spectacular.

Let’s start with left guard. I don’t think anyone doubts that 2013 free agent signee Donald Thomas (left) is a better-than-average starter if he’s healthy. He missed virtually all of last season with two serious injuries sustained on a single drive, but has generally proven durable in his career up to that point and should be ready for training camp. So that’s one position we can call solidly filled.

As far as the other two positions, I think the Colts have added by subtraction by cutting ties with erstwhile starters Samson Satele and Mike “Big Greasy” McGlynn.

Their expected replacements are 2013 draft picks Khaled Holmes and Hugh Thornton (left). That might make many Colts fans sigh a little because Thornton didn’t play consistently well in his rookie season, and Holmes barely played at all while Satele and McGlynn were getting his snaps despite being terrible. But those fans are forgetting one of the most sacred commandments of NFL football: Never judge an offensive lineman by his rookie season. Other than maybe Joe Thomas, virtually all rookie offensive linemen are overwhelmed by the speed, power and trickery of pass rushers in the pro game. Look at Eric Fisher, Luke Joeckel and Lane Johnson — the first, second and fourth picks of the 2013 draft — they were all hammered as rookies, but few doubt that they’ll have long and successful pro careers.

And keep in mind that Fisher, Joeckel and Johnson all had the benefits of training camps and the preseason, while Holmes and Thornton both missed theirs due to injury. So, if effect, they were thrown to the wolves basically out of college.

Thornton played extensively after Thomas went down and had an inconsistent season, with every highlight block erased by a whiff on the next play. He was definitely NFL starter quality when it came to pass blocking, but was something of a liability as a run blocker. When I look at the tape, what I see is an over-eager youngster prone to mistakes through inexperience and a desire not to screw up. There’s a good chance that’ll go away with reps and good coaching, as long as his confidence stays intact.

Holmes hardly played, but when he did, he handled himself with aplomb. But his 12 snaps were far too small a sample size to make any real projections about his abilities. But he was a great college player, and a year in the system should have helped him develop into a viable starting candidate.

To add to the competition, the Colts signed two veterans with NFL starting experience.

One was center Phil Costa (left). Technically superior but undersized, he went undrafted in 2010 and signed with the Cowboys. By 2012, he had fought his way from fourth-string to a 16-game starter. But the Cowboys used their first-round pick in 2013 on center Travis Frederick, and Costa was relegated to backup, playing just a single down on offense.

A lot of Colts fans have pointed out that the Cowboys were in a hurry to replace him as a starter, and in no hurry to re-sign him, so he can’t be all that great. While that is technically correct, I think that the whims and wisdom of Jerry Jones are not always great indicators of true personnel value.

While it’s true that Costa was sometimes overpowered when he was playing for the Cowboys and will never be confused for Alex Mack, he was a consistently sound blocker who could have walked in at any time last season and been an instant upgrade over Satele or McGlynn.

The other signee is guard Lance Louis. Before missing the last two seasons recovering from a horrifying ACL tear, Louis was an up-and-coming starter for the Bears. If he’s right, he could be a steal. Colts GM Ryan Grigson, for one, expects him to compete for a starting job.

And there’s always recently re-signed Joe Reitz. Yes, he looks more like a basketball center (which he was in college) than an NFL guard, and he has been around seemingly forever without nailing down a starting job, but he has played well in a support role at both guard and tackle, or as a sixth lineman. I’ve always had a soft spot for Reitz, whose development has been hampered by position switches and injuries, and think he’s a valuable spare part who can fit in anywhere on the line, including tight end.

There’s also Xavier Nixon, who has the inside track to be the Colts’ third tackle, has also played guard. He’s not great at it, but he can get by.

And, finally, the Colts also have Austin Thomas, who has knocked around the league for a few years after a distinguished career at Clemson.

So, although the Colts don’t have any world beaters between the tackles, I just don’t see them getting an upgrade in this draft. The quality of prospects is just not that great, and I’d really hate to see them make a Mike Pollak-like reach. If they open the season with, barring injury, Thomas at left guard, Holmes at center, Thornton (or perhaps Louis) at right guard and the others as backups/reserves/role players, I think they’ll be fine.

If you’d like to know more about the Colts offensive line personnel and play in 2013, please read Ben Gundy’s remarkably detailed and, in my opinion, accurate assessments at the Colts Authority.