As an agent with a LB on this very team, let me share my thoughts on the depth chart. I can see everyone's builds except for temujin83's. However, the combine stats for both his LBs are identical, so I am assuming he has 2 identical dots whose shared build is listed in the OP.
First observation: Having 2 identical dots intrinsically reduces their value on the same team. If a defensive scheme calls for a player archetype that is similar to your build, your 2 dots will be fighting for the same plays. It would have been better to create 2 LBs that can each perform a specific function on the team unless you are absolutely sure the defensive scheme needs 2 players of the same archetype at the same time (and even then, it is a risk, as the meta of the game changes over time, and so defensive schemes will need to shift to stay competitive).
There is a pretty clear pecking order in terms of raw play counts: we have a #1, #2 and #3 LB, and 2 #4 LBs. The top three LBs have about a 10 play per game gap between each other, and then there is a bit more than a 15 play per game gap to the 2 backups who have near identical play counts. For the record, my dot is #3. It is also worth stating that conditioning and toughness are largely identical across all 5 LBs, so these play counts are clearly a result of the DCs decisions vs guys getting gassed.
Going through the builds one by one, LB1 shades towards causing fumbles, LB2 is more a wrap up guy, LB3 is balanced and LB4s are big hitters. All 5 LBs have invested in tackling skills though, just doing it slightly differently, and are all generally competent tacklers, so nothing to really differentiate here in my view. Tackling skills in this group may dictate when and where they play, but not if they see the field in general.
Things start to differentiate in the "defense" skills. LB3 is best at breaking run blocks on the team, whereas LB1 is best at standing up to a run block. LB2 is mediocre against run blocking, and LB4s are absolutely terrible. Nothing invested in either skill, and the lowest balance on the team by a wide margin.
Second observation: Your LBs are totally unplayable against run focused teams, which happens to be our biggest competition. This is going to impact their overall play count and relegate them to ST in these games. Honestly, the defense would be much stronger if one of your LBs was cut and a run specialist was brought in instead, as the team is pretty thin with only 3 LBs that can play when we face a running team.
Moving onto the other defense skills, LB1 is pretty average and LB2 and LB3 are better at pursuit than LB4s. The only thing LB4s have going for them here is high defensive consistency, but at the cost of zero blitz awareness. In my view, defensive consistency doesn't help a LB do anything specific, whereas a lack of blitz awareness limits when and where they can play. It helps against a run team, but LB4s already can't be played against a run team, and it helps against a pass team, but it really hurts against a balanced team. Not necessarily enough to make them unplayable against balanced teams, but it doesn't help and they already can't play against run teams.
On the pass coverage side of things, LB1 and LB2 are basically incompetent. This should be where your LB4s shine and earn playing time, but the thing is LB3 is much better in pass coverage since LB4s can't play in zone and are very easy to shake despite being built to play man, so they are the second LB on the field at best in passing situations. Which means to see field time, the DC needs to want 3 LBs in pass coverage vs having some blitzing from that position. It doesn't help that a DC might want to run nickel or dime in passing situations pretty often.
On the pass rushing side of things, LB1 is the only player that can blitz, which is probably why he sees more playing time than any other LB on the team. Despite weaknesses, he possesses a unique skill, so when the DC needs an LB to blitz, he wants LB1 on the field and no one else. In passing situations, this is going to eat into LB4s playing time considerably, as DBs are going to be doing the bulk of the coverage work and there is a stronger LB for that when desired.
On the physical side of things, LB4s really have nothing going for them. LB2 is faster and has more to offer elsewhere. With the low quickness, I would say LB3 is also faster except on special teams. LB4s are lower than everyone else in balance and footwork, further reinforcing how easy it is to neutralize them with blocking. Everything else is pretty similar across all the LBs, except LB4s also have no intimidation despite having a tackling build set up to be more of a big hitter. The only thing LB4s really have going for them in this category is a lot of sprinting, which further reinforces playing them mostly on special teams.
Third observation: It has already been established that LB4s can't play at all against run focused teams, when LBs generally see more playing time. Additionally, they are probably third choice behind LB1 the blitzer and LB3 the pass coverage expert against pass focused teams, when LBs generally see less playing time. The basically leaves their only real opportunity to play against balanced teams. The thing is, the LB4s are not really generalist LBs either. LB2 is, and after that, LB4s are still competing with LB1 and LB3 if the DC wants to throw out an LB to blitz or cover a receiver.
Finally, temujin83, you state that your LBs aren't such a liability in the run game because of revpancake and pancaked stats. Thing is, your LBs get pancaked against run focused teams and get their revpancakes against pass focused teams. Those stats are misleading and they don't help against run focused teams. It doesn't help that the top 3 teams in our league are run focused, including our team. If we want to win the ship, we have to beat 2 other very good run focused teams, which your LBs are largely useless against.
Honestly, if you'd like them to see more playing time, my only suggestion would be to move one of them to another team if you can. It is too late in the build to differentiate them enough at this point, and so they will always be competing against each other for playing time on the same team.
After that, they need to find a niche. Not only are they not superstars, they don't even boost, so trying to build a good general/balanced LB is not a good decision. Therefore, I wouldn't even bother addressing the run block breaking skills at this point. Turn them into pass coverage KL specialists. That means more pursuit (always useful), much more coverage technique (if you ever want to play man effectively), more zone awareness (LBs in pass coverage are going to be in zone - it in unavoidable), more man awareness (if you really want to leverage the investment in deflecting), more intimidation (to wear down receivers as the game progresses and leverage the power tackling), more quickness (useful in both man and zone). Some nice to haves would be some diving and vertical, especially considering they will be cheap to boost a little.
If you don't have the SP to do all that (although if you boosted, you really would), maybe focus more on the KL angle rather than just general pass coverage. Which means you could deprioritize coverage technique, which is going to cost a lot of SP to take to a reasonable level.