I don't think you EVER play to lose (a mentality which doesn't exist, IMO in professional sports) BUT you should play to see what you have in your 'bench'. We see it all the time in other sports when EITHER the playoff spot is locked or the team is eliminated. The problem has been on this team that they have remained successful for so long. This stretched the cap for the team and diminished 'known' depth at positions. Also, with the cap-strapped situation being as it were, the team employed 'stashing' young talent in the hopes that the vets (if they remained healthy) could finish out their time while the team felt they had a decent prospect ''waiting in the wings".
They got caught doing this with lesser players like Joe Long who was picked off and is now with Chicago finishing his apprenticeship as well as some hungry players like Al Woods who had to escape out the back door to Tennessee. Arnfelt is the next Woods IMO, which is why he was not played as much as he might have warranted. Sometimes you get caught in this scenario, especially if you don't have the cap to keep the developing players on the roster. Woods probably thought he should have been starting (or getting more reps) over Hood, who was likely gone as a FA. The team didn't want another scenario like they had with McClendon, who got some reps and was pursued by the Packers causing us to sign him to a larger contract than we would have had to if he had no tape. Who knows who else on the team felt this way in the past. Maybe Moye is tearing it up in practice and they didn't want to risk losing him by playing him too soon? (I doubt it though).
The problem is, we were forced to see what we had in Worilds, Heyward, Cotchery, Wallace(c) and a host of lousey TEs due to injury and poor play in front of them. We likely would still have been able to sign Worilds (without a tag), Cotch and Wallace without too much competition IF they hadn't shown their potential to other teams. Wallace would have been signed for the minimum instead of getting a new 'reflective' contract. It happened, we dealt with it and we lost some money and a few players.
Very few teams have had to 'try' to maintain cap compliance through 6-8 years of competitive play. We saw what happened to 'role' players in SF, Carolina and Seattle this year when they had success. This has been a fight the Steelers have been in for two decades. It's not easy staying at the top when everyone else wants a piece of what you have. I don't necessarily agree with how they approached the playing time of younger talent BUT I understand what they were trying to do. I would have liked to see some younger guys in the 'mix' over the last few years BUT we see what happens to those players if they 'flash' potential. It is a fine line that SOME players respond to by trying harder while some get impatient and make a change. We weren't likely to win our 7th the last 2 years but we have to realize MOST teams go into full rebuild mode after a run like we had.