I don't strictly disagree with you, but keep in mind that Ensberg was designated for assignment and Giles was non-tendered completely. Trachsel was neither and still on Baltimore's active roster and therefore the Cubs couldn't just pull him off the scrap heap for a pittance.
They'd have Plácido Polanco still, probably at 2nd. Wouldn't necessarily make them good, but it wouldn't hurt them. Boston would have Hanley Ramirez at shortstop and would have had the services of Jeff Bagwell for all those years.
He was going for a foul ball, couldn't get it and then fell over the plexiglass ball shield in front of the seats at that level. Probably bruised/pulled something in his midsection.