If we're talking about just the biggest contracts given to pitchers over 30 or 31/32, IMO there are too many that worked out well or okay to use the word "always". It's not like there are hundreds and hundreds of bad big deals for aging pitchers.
There are certainly some real duds, especially in the early days of free agency. How many of these do you think were bad to awful? How many were okay? How many were good to great?
Highest paid pitchers of all time (some were under 30 when signed):
Starting pitchers
The highest-paid starting pitchers, by average annual value:
1. Justin Verlander, $33,000,000 (2020-21)
2. Zack Greinke, $32,500,000 (2016-21) (reduced for deferrals)
3. David Price, $31,000,000 (2016-22)
… Clayton Kershaw, $31,000,000 (2019-21)
5. Clayton Kershaw, $30,714,286 (2014-20)
6. Max Scherzer, $30,000,000 (2015-21)
7. Jacob deGrom, $27,500,000 (2019-23)
8. Jon Lester, $25,833,333 (2015-20)
9. Justin Verlander, $25,714,286 (2013-19)
10. Chris Sale, $25,600,000 (2020-24)
11. Felix Hernandez, $25,000,000 (2013-19)
… Stephen Strasburg, $25,000,000 (2017-23)
… Jake Arrieta, $25,000,000 (2018-20)
14. Zack Greinke, $24,500,000 (2013-18)
15. CC Sabathia, $24,400,000 (2012-16)
16. Cole Hamels, $24,000,000 (2013-18)
… Cliff Lee, $24,000,000 (2011-15)
18. Patrick Corbin, $23,333,333 (2019-24)
19. CC Sabathia, $23,000,000 (2009-15)
20. Johan Santana, $22,916,667 (2008-13)
21. Masahiro Tanaka, $22,142,857 (2014-20)
22. Jordan Zimmermann, $22,000,000 (2016-20)
23. Johnny Cueto, $21,666,667 (2016-21)
24. Matt Cain, $21,250,000 (2012-17)
25. Yu Darvish, $21,000,000 (2018-23)
26. Rick Porcello, $20,625,000 (2016-19)
27. Tim Lincecum, $20,250,000 (2012-13)
28. Roy Halladay, $20,000,000 (2011-13)
29. Adam Wainwright, $19,500,000 (2014-18)
30. James Shields, $18,750,000 (2015-18)
31. Carlos Zambrano, $18,300,000 (2008-12)
32. Roger Clemens, $18,000,000 (2005)
. . . Barry Zito, $18,000,000 (2007-13)
. . . Jeff Samardzija, $18,000,000 (2016-20)
35. Tim Lincecum, $17,500,000 (2014-15)
. . . Homer Bailey, $17,500,000 (2014-19)
37. Jake Peavy, $17,333,333 (2010-12)
38. Josh Beckett, $17,000,000 (2011-14)
. . . Jered Weaver, $17,000,000 (2012-16)
. . . Nathan Eovaldi, $17,000,000 (2019-22)
. . . Miles Mikolas, $17,000,000 (2019-23)
42. A.J. Burnett, $16,500,000 (2009-13)
. . . John Lackey, $16,500,000 (2010-14)
44. Andy Pettitte, $16,000,000 (2007)
. . . Andy Pettitte, $16,000,000 (2008)
. . . Justin Verlander, $16,000,000 (2010-14)
. . . Anibal Sanchez, $16,000,000 (2013-17)
. . . Hiroki Kuroda, $16,000,000 (2014)
. . . John Lackey, $16,000,000 (2016-17)
. . . Scott Kazmir, $16,000,000 (2016-18)
. . . Rich Hill, $16,000,000 (2017-19)
52. Jason Schmidt, $15,666,667 (2007-09)
53. Jake Arrieta, $15,637,500 (2017)
54. Felix Hernandez, $15,600,000 (2010-14)
55. C.J. Wilson, $15,500,000 (2012-16)
56. Max Scherzer, $15,250,000 (2014)
57. Mike Hampton, $15,125,000 (2001-08)
58. Kevin Brown, $15,000,000 (1999-2005)
. . . Derek Lowe, $15,000,000 (2009-12)
. . . Hiroki Kuroda, $15,000,000 (2013)
. . . Hisashi Iwakuma, $15,000,000 (2016-18)
62. Roy Oswalt, $14,600,000 (2007-11)
63. Mark Buehrle, $14,500,000 (2012-15)
. . . Jake Peavy, $14,500,000 (2013-14)
65. Mark Buehrle, $14,000,000 (2008-11)
. . . David Price, $14,000,000 (2014)