This is true. If you look at season totals from last year, it's pretty clear who the more effective back was. Again, I'm not knocking Hightower at all, just doing this for the sake of comparison.
Ingram 2015 season 166 rushes...769 yards...4.6 ypc
Hightower 2015 season 96 carries...375 yards...3.9 ypc
That's a significant statistical difference. Ingram has a place in the offense and he can be very useful in short yardage situations, and he has been much of the season up until the last 2 games. I'm not convinced giving up on him is the right move at this point, but that can always be reevaluated at the end of the season.