Yup. Most teams end up cycling through closers every couple two tree years just because it's pretty rare for relievers to be both healthy & effective for multiple seasons consecutively. Looking at the reliever leaderboard since 2000, Mariano is still 1st with 29.2 WAR & he hasn't pitched in eight years. Chapman is second, 9 WAR behind Rivera, leading a group of five guys (Kenley, Nathan, Kimbrel, Papelbon) grouped between 19-20 WAR. Rounding out the top 10 are K-Rod, Wagner, Soria & Rafael Betancourt around 15-16 WAR. Even starting in 2010, to make it a little more contemporary there is a pretty big drop off from the three active guys in the 19-20 WAR group down to David Robertson in 4th at 13.3 WAR. Then a grouping of Holland, Betances, Melancon & Doolittle around 11-12 WAR. I feel like a lot of baseball fans probably think something like half of the top ten relievers over the last ten to twenty years suck.