Oli Marmol's lineup construction
Several times during the regular season when the Cardinals were struggling offensively, Marmol consistently kept the same lineup for several games. It didn't help the Cardinals break out of their funk.
One common mistake he made however was constantly sitting several of his regular starters in the final games of road series. On these days, players such as Motter and Alec Burleson were given starts. The reason behind sitting his stars was also the same each time. Marmol claimed that he was giving players like Arenado and Paul Goldschmidt "scheduled days off."
More often than not, the Cardinals would lose these games, as the lineup they put on the field could not hold a candle to their opponent's. And so, it became increasingly clear that Marmol was not putting the best possible product on the field.
Though the Cardinals were already well out of the postseason race, it was something that frustrated fans a great deal, as it convinced them that the Cardinals were not trying to win games. Marmol's constant use of Burleson and Motter was certainly perplexing, and it ran the team into some trouble various times during the season, typically costing them games they needed to win.