A lot of the Cubs starters are vastly underperforming career numbers. Swanson (career OPS 733, this year 650), Happ (791, 718) Hoerner (714, 661) and Bellinger has gone back to being mediocre. They might be banking on those guys to all start hitting over the next month. In regards to their prospects, they could probably call up Horton at some point but even if he turns things around in AAA he will probably have an inning restriction.