Trying to explain the AL teams with the biggest increases in starter ERA

[Frobby]

Here are the five AL teams who have seen the biggest increases in their starter ERA:

TOR +1.19

BAL +1.15

CWS +0.71

DET +0.46

SEA +0.40

What has gone wrong for these teams?

Toronto (+1.19) - In the offseason, they let R.A. Dickey, who was their worst starter (4.46 ERA in 169.2 IP) walk, and this year they've inserted Francisco Liriano (5.88 ERA) in his place.   Oops, that didn't work out!    Beyond that, Aaron Sanchez only has made 8 starts this season, and J.A. Happ has only made 14, and both those pitchers' ERA's have gone from the low 3's to the low 4's.    Marco Estrada has seen his ERA increase by nearly 2 runs per game.   Joe Biagini, pressed into service as a starter due to Sanchez's injury, has been ineffective in that role (5.60 ERA).    The one bright spot for the Jays has been Marcus Stroman, who has lowered his ERA by over a run.   

Baltimore (+1.15) - The O's traded Yovanni Gallardo (5.42 ERA in 118 IP) and replaced him with Wade Miley, acquired at the trade deadline last year (5.60).    They inserted Dylan Bundy (4.53 ERA) as a full time starter instead of giving 25 starts to Mike Wright (6.22 ERA as a starter last year) and Tyler Wilson (5.67 last year).     So far so good, right?    But Chris Tillman began the year on the DL and has seen his ERA rise by almost 4 runs/game, Kevin Gausman has seen his ERA rise by 1.75 runs/game (that is hopefully dropping now), and Ubaldo Jimenez has seen his ERA rise by more than 2 runs a game.    It was really tough to foresee this level of implosion.

Chicago (+0.71) - Some increase was highly likely here, since the White Sox traded their ace, Chris Sale (3.34 ERA in 226.2 IP last year).   They've also been hurt by an injury to Carlos Rodon (4.04 ERA in 165 IP last year, only 6 starts so far this year).    Derek Holland, signed as a free agent, has not worked out (5.42 ERA in 196.1 IP) and their other big offseason acquisition, Mike Pelfrey, has been predictably blah (4.73 ERA).    And of course, they've now traded away Carlos Quintana.

Detroit (+0.46) - The Tigers traded Pelfrey (5.07 ERA in 2016) in the offseason, but that hardly matters.    Bigger issues are the 1+ increase in Justin Verlander's ERA and the nearly two run increase in Daniel Norris ERA, and Jordan Zimmerman being a run worse than last year.

Seattle (+0.40) - The Mariners traded Wade Miley a year ago (4.98 ERA for them in 112 IP) and inserted the pitcher they acquired, Ariel Miranda (4.31 ERA in 121 IP) in what has turned out to be an upgrade for them.    They traded Taijuan Walker (4.22 ERA in 134.1 IP) away in the offseason, and acquired Yovanni Gallardo (5.34 ERA in 97.1 IP) - not an upgrade.   Hisashi Iwakuma (4.12 ERA in 199 IP last year) has made only 6 starts this season, and King Felix has made only 12 starts.   

I look at all this and say, pitching is largely a crapshoot.    If I have time later, I may try to analyze the 5 teams whose rotations have improved the most (Minnesota, Houston, Tampa, New York and Kansas City).    But the improvements of those teams are much more modest than the declines of the Blue Jays, Orioles and White Sox.