Why Dernard Span has recently become out of the question for the Reds

Dernard Span has recently become out of the question.

MLBTradeRumors has announced that in exchange for Dernard Span, the Twins want a MLB starting pitcher. I see no way no how the Reds will do this.

As of July 29th, the Reds have used the same 5 starting pitchers the entire season. The staff's starting pitchers claim 41 of the Reds 61 wins (an overall 41-26 record for starters.) 67% of the wins. Nothing is wrong with the Reds current rotation, and actually they are on a huge roll, the Reds winning 10 straight.

 Leake has the worst record as a starter on the Reds roster, (4-6) but there is little to no chance Leake is a trade item. Bailey is the most likely out of the rotation to be traded, but I highly doubt it.

 Span is not an essential, so I think the Reds just threw out all thoughts on acquiring Span.