This isn't at all common in the nfl. It took the saints drew brees' AFTER his contract expired to re-sign him. Look at all the players that got a franchise tag last year. Teams don't re-sign player this early as often as you are making it out to be.
And as great as byrd and levitre are, calling them leaders is a bit of exageration. Especially on levitre. I wouldn't call either of them leaders. Kyle Williams, George Wilson, Fitz, and freddy, THOSE are leaders. Hence why freddy got extended (plus he outperformed his contract).
I'm sorry. I just don't see the "risk" of losing one of them of we don't sign them right now. Would it be that bad to sign them in late season? Hell, if all else fails, we can franchise one of them. This risk is so minimal