need clarification - near term parallel shift / shift over 12 months

CFA Level III
#1

1.A manager expects small very near term parallel upward shift

conclusion no clear winner for bullet barbell and ladder

  1. for large upward parallel near term

Barbell

  1. large parallel downward shift over 12 months

No clear winner

Can someone give clarification why does it make difference with near term /over 12 months and large/small shift?

#2

Not much information. The barbell has the best return because it has highest convexity.

Not syure what the long term or short term stuff is. Need more details. Maybe the short term causes short term rates to drop but not long time, or the rates on the long term move too much and convexity doesnt make up the difference.