Right and "top backups" shouldn't be your starter for 3-4 years, is all. Tomlin thinks starting a "backup" as starter is a great plan, not the brightest HC out there.
Tomlin inherited a great OL from Cowher. A few year later, Arians proclaimed that you didn't need a great OL if you had good enough skill players. That is somewhat true. Ben, Bell and AB overcame mediocre OL play for years. The Steelers got lucky with Villanueva and Munchak coaching up some guys.
They really messed up when they threw Moore and Kendrick Green out there to start.
Here's the sad draft history of OL under Tomlin. Pouncey is was really the only 1st rounder that Tomlin/Colbert targeted. They ended up with Decastro when he fell much further than anybody expected. They got lucky with undrafted Villanueva and 7th rounder Kelvin Beachum. Aside from that a lot of misses on later round guys.
Then you look at the last 2 years and you see the commitment to building the OL.
2007 5 Cam Stephenson
2008 4 Tony Hills
2009 3 Kraig Urbik 7 AQ Shipley
2010 1 Pouncey 5 Chris Scott
2011 2 Marcus Gilbert 6 Keith Williams
2012 1 Decastro 2 Mike Adams 7 Kelvin Beachum
2013 none
2014 5 Wesley Johnson
2015 none - Free Agent Villanueva
2016 4 Jerald Hawkins
2017 none
2018 3 Chukes Okorafor
2019 7 Derwin Gray
2020 4 Kevin Dotson
2021 3 Kendrick Green 4 Dan Moore
2022 none
2023 1 Broderick Jones 7 Spencer Anderson - Free Agent Semualu
2024 1 Troy Fautanu 2 Zach Frazier 4 Mason McCormick