Sorry, but that second sentence doesn’t make any sense. I give up, so I’ll leave it as this.
There is a perception rightly or wrong that taking penalties when behind on the scoreboard is more difficult and that fewer in such circumstance are converted. There is a body of statistical evidence that supports this hypothesis too. All the ABBA system attempts to do is divide the number of shots a team will have to make when behind on the scoreboard equally between both teams, rather than have this burden placed primarily on Team B. Under the old system, Team B takes far more penalties under pressure than Team A, if both teams convert equally long term, in fact Team A would never have to take a penalty under scoreboard pressure should they not miss.
FWIW, I don’t believe this change needed to be made. The most comprehensive collection of penalty shootouts that I’ve seen suggests that the advantage of going first versus second was about 52% v 48%. This new system may get it close to 50-50, but even if it does, it won’t be apparent.