Are you really sure about this "no spending trains while not on a team" solution to SSB? Consider this:
Life cycle of the new SSB:
Build player on day 28. Don't sign with a team, so I start life with 7 trains that I can't spend.
On day 31, I sign with a d-league team that's already played its last regular season game (can sign with d-leagues at any time). This allows me to start spending trains before I hit the max of 14 (I have 13 at this point).
From day 31 on, I'm freely spending trains and not accruing any game XP at all.
Sometime during the offseason, sign a sweet cash deal so I've got fat bank for all my future training. Reneg a couple of times if needed so that cash will never be a problem.
Assuming an 18 day offseason, I've got 7 trains (creation) + 24 trains (first season) + 36 trains (offseason) = 67 trains when the next season starts.
Cut the player before the first game (on either day 1 or day 2). Wait 7 days, while I gain trains without gaining any game XP. On day 8 (or 9), sign with a new team. Immediately spend some trains so I don't go over the 14 limit. Wait the minimum period (3 days?) before being released. With proper planning, that means I'll gain exactly half of one games' worth of XP. It's now day 11 or 12 and I've still never missed a train or gained any game XP.
Wait 7 more days while I wait for my trains to hit 14 again. On day 18 or 19, sign with another team. Spend trains. Wait 3 days, gaining half of 1-2 games of game XP. Cut player on day 21 or 22, after spending all trains.
On day 28 or 29, you actually start missing out on some trains. But not to worry! You're still only level 3 or 4, so on day 31 you can sign with a d-league team, so you only miss about 6 trains.
So over the course of your first 50 days, you gain the equivalent of 1 to 1.5 games' worth of game XP, and something like 90-95% of the trains.
It might get tougher the second season; I don't know the math well enough to tell whether you can make it two seasons following this model without going over level 7 (the d-league limit). At some point, you'll have to start missing out on a few more trains because you'll be stuck off of a team from day 28/29 to 41.
Sure it's more complicated than the old SSB method, but it's still possible, and a lot of people will still do it unless more is done to stop SSB.
Sorry for the TL;DR post, but I felt it needed some explanation. Feel free to wait until later to answer.