"Starter" is a relatively arbitrary term when it comes to a football team – just think about defensive snap counts dependent on formation and opponent. However, there are a few position groups where starters usually are the players that play the vast majority of snaps. Quarterback is one of those positions, kicker is another. The five offensive line spots are as well.
Looking at the offensive line, we know most of the starters. Nate Solder and Sebastian Vollmer will play on the left and right end of the line, respectively. Bryan Stork, who missed the last two practice sessions but is confident that he will be ready on Thursday, will be the team's starting center. Rookie Tre' Jackson looks like the odds-on favorite to start at right guard.
That leaves one spot open: left guard.
Predicting Thursday's starting left guard is a tough task because we don't know for sure if Stork will be ready to play. But even if he isn't, opening day is not an isolated event. The second year center will start again rather sooner than later and the week 1 offensive line might indicate who are the top interior options right now.
That being said, here are the contestants for the Patriots' opening day starting role (in alphabetical order):
In 2014, the 25-year old was the top interior back-up and started five games in place of an injured starter (among them, the AFC Championship Game). At times, he looked very comfortable and like a solid contributor, but he struggled against high-level competition. While Kline's ceiling is more or less known at this point in his career, his experience playing alongside Nate Solder and, should Stork be out on Thursday, Ryan Wendell, might give him the edge to start the game. Even if Stork is ready to go, Kline might be the top option at left guard given his combination of experience (over Mason's) and offseason participation (over Wendell's).
With Wendell injured, the rookie saw a lot of playing time with the would-be top offensive line during training camp and the preseason. Because of that, the coaching staff might be inclined to start the 22-year old instead of the veterans competing with him for that left guard role. Starting Mason would be somewhat of an experiment, though, since his preseason tape reflects his college game: he is a really good run blocker and strong at the point of attack but is somewhat inconsistent when it comes to pass protection, in part because of his foot-hand-coordination (something that can be coached but needs time). It has to be seen if his potential and preseason growth is enough to earn him a starting role against the Steelers and possibly beyond.
The seven-year veteran started last year on the bench but eventually became the Super Bowl champions' most reliable interior offensive lineman. With last year's starting left guard Dan Connolly retired, Wendell looked like the prime candidate to replace him as the left guard especially due to his experience. However, missing almost all of training camp and three of four preseason games gave others – particularly Mason – a chance to get some reps. Whether those reps and Mason's potential are enough to replace Wendell on the starting offensive line remains to be seen. At this point in time, though, the known commodity that is Ryan Wendell still looks like a starter on opening day 2015: either as the team's center (as Stork's possible replacement) or its starting left guard (as an experienced and steady presence).
In 2014, the Patriots – especially after trading Logan Mankins – entered the season with lots of questions surrounding their offensive line. The team needed until game five to finally find answers. Even though there are also uncertainties along the 2015 line, there is really only one position to address and only one question to answer this year: potential or experience?