I won't speak for Slateman, but I think it's a caveat that going all-in in the free-agent market for starting pitching because starting pitching is the best route to the playoffs might not be wise.
Look at the Orioles' gamble a few years' ago. There were 11 starters in MLB Trade Rumors' list of 2017-18 Top 50 MLB Free Agents (Darvish, Arrieta, Tanaka, Lynn, Cobb, Sabathia, Cashner, Chacin, Vargas, Tillman, Pineda). The Orioles signed three of them. It was their gamble to take one last shot at the playoffs, rather than rebuild, and 2018 was a disaster for Baltimore.
Another caveat: among the highest-paid starting pitchers in MLB history are these below. AAV and term of contract are from Cot's. Pitching WAR is from Baseball Reference. Some good seasons in there for a few of the players but a lot of overpaying. King Felix looked like a win for the first few years of his contract, but then fell off a cliff. Others had inconsistent up-and-down years. And others like Scott Kazmir's 2016 deal were terrible.
Jon Lester, $25,833,333 (2015-20); 2.7, 5.6, 0.7, 3.4, 1.3, 1 year left
Felix Hernandez, $25,000,000 (2013-19); 5.3, 6.4, 4.5, 1.4, 0.7, -1.2, -0.6
Jake Arrieta, $25,000,000 (2018-20); 2.9, 0.9, 1 year left
Jordan Zimmermann, $22,000,000 (2016-20); 0.4, 0.2, 0.6, -0.3, 1 year left
Johnny Cueto, $21,666,667 (2016-21); 5.5, 2.0, 1.3, 0.1, 2 years left
Matt Cain, $21,250,000 (2012-17); 3.8, 0.7, 0.0, -0.7, -0.7, -0.4
Yu Darvish, $21,000,000 (2018-23); -0.1, 3.3, 4 years left
Rick Porcello, $20,625,000 (2016-19); 4.8, -0.2, 3.1, 1.2
Tim Lincecum, $20,250,000 (2012-13); -1.7, -0.5
James Shields, $18,750,000 (2015-18); 2.2, -1.1, 0.3, 1.4
Carlos Zambrano, $18,300,000 (2008-12); 4.2, 3.0, 2.6, 0.7, 0.7
Homer Bailey, $17,500,000 (2014-19); 1.5, -0.1, -0.5, -0.8, -1.5, 1.8
Josh Beckett, $17,000,000 (2011-14); 5.8, 0.9, -0.8, 2.0
Jered Weaver, $17,000,000 (2012-16); 4.3, 3.6, 2.8, 0.4, -0.7
A.J. Burnett, $16,500,000 (2009-13); 4.5, -0.7, 0.0, 2.6, 1.9
John Lackey, $16,500,000 (2010-14); 1.8, -1.8, 3.0, 1.0, missed one year
John Lackey, $16,000,000 (2016-17); 2.8, 1.2
Scott Kazmir, $16,000,000 (2016-18); 0.5, did not play last 2 years of contract