Start Here: A Pitching Line Is Four Separate Questions
When you open a matchup page you see something like 9-9, 4.21 ERA, 1.18 WHIP, 159 K, 37 BB and your eye goes straight to the ERA. That is the wrong habit, and tonight's card is a good place to break it, because the pitcher with the biggest bet behind him has a perfectly ordinary ERA.
Those numbers answer four different questions and they can disagree with each other completely.
Beginner Note: ERA
Earned run average is how many earned runs a pitcher gives up per nine innings. It is a results number. It counts what actually crossed the plate, which means it carries every bad bounce, every error that was not scored as an error, and every reliever who came in and let his runners score. A good pitcher on a bad defence has a worse ERA than he deserves, and the reverse is just as true.
Beginner Note: WHIP
Walks plus hits per inning pitched. It counts traffic, not damage. A 1.10 WHIP means about one baserunner an inning. WHIP does not care whether those runners scored, which is exactly why it is more stable than ERA month to month. If ERA and WHIP disagree, WHIP is usually the one telling you what the pitcher did and ERA is telling you what happened to him.
Beginner Note: Opponent Batting Average
The batting average hitters have posted against him. This isolates contact. A pitcher with a low opponent average and a high WHIP is walking people. A pitcher with a high opponent average and a low WHIP is getting hit but not giving anything away for free. The two numbers together tell you which kind of trouble he gets into.
Beginner Note: Strikeout To Walk Ratio
Strikeouts divided by walks. This is the control number and it is the one that travels best from month to month. Anything above 3.0 is good. Below 2.0 is a warning. A strikeout removes a hitter with nothing behind it. A walk hands over a base for free. The ratio between them is close to a pure measure of command.
The Eight Starters Tonight, On All Four Numbers
Here is the whole card in one table. Read across, not down.
| Pitcher | Team | ERA | WHIP | Opp AVG | K/BB |
|---|---|---|---|---|---|
| Payton Tolle | Boston | 3.09 | 1.09 | .218 | 4.03 |
| Peter Lambert | Houston | 3.66 | 1.23 | .222 | 2.45 |
| George Kirby | Seattle | 4.02 | 1.33 | .282 | 3.71 |
| Anthony Kay | Chicago | 4.09 | 1.34 | .256 | 2.30 |
| Jacob deGrom | Texas | 4.21 | 1.18 | .234 | 4.30 |
| Ian Seymour | Tampa Bay | 4.21 | 1.15 | .225 | 4.00 |
| Gage Jump | Athletics | 4.69 | 1.46 | .259 | 2.31 |
| Robert Stock | New York | 7.40 | 1.94 | .307 | 1.62 |
Now Read It Properly
Sort that table by ERA and Jacob deGrom is fifth of eight. Sort it by strikeout to walk ratio and he is first. Sort it by WHIP and he is third. Those are the same twenty five starts described three different ways, and the three ways do not agree.
What is actually going on: deGrom has struck out 159 hitters and walked 37. Almost nobody reaches base for free against him and opponents hit .234. His 4.21 ERA is telling you that the runners who did reach found a way home. The 4.30 strikeout to walk ratio is telling you what he is doing on the mound. Those are different sentences and the second one is more useful when you are trying to guess about tonight.
Now do the same with Gage Jump on the other side. A 4.69 ERA looks only half a run worse than deGrom's 4.21, which makes the game sound close. Then look left: 1.46 WHIP against 1.18, and 42 walks in 88.1 innings against 37 in 130.1. That is nearly one and a half baserunners an inning, and it is the number that turns a one run deficit into a four run deficit in a single frame. The ERA gap flattered him. The WHIP gap did not.
Beginner Note: Why This Matters For A Run Line
Tonight's biggest play is Texas at minus 1, which needs the Rangers to win by two or more. A moneyline only needs a win. That extra run has to come from somewhere, and the usual source is not the favourite's offense, it is the opponent's pitcher handing out free baserunners in one bad inning. That is why WHIP and walks matter more on a run line than on a moneyline.
The One Line That Is Not Close
Look at the bottom row. Robert Stock, starting for the Mets in Tampa: a 7.40 ERA, a 1.94 WHIP, a .307 opponent average and 21 strikeouts against 13 walks. All four numbers agree, which almost never happens, and they agree in the same direction.
There is also a fifth number hiding underneath: 20.2 innings. That is not a season, it is about four games. When a club sends out an arm with twenty innings on it, what you are usually looking at is a bullpen game, where the starter is expected to cover two or three innings and five relievers cover the rest. That is why the Rays are minus 168 tonight and why the number does not look generous.
Beginner Note: Sample Size
Twenty innings is small enough that one bad afternoon moves an ERA by more than a run. Be careful reading anything into a line built on four or five appearances, in either direction. The reason to respect Stock's numbers tonight is not that 7.40 is precise, it is that the club's plan clearly does not involve him going deep.
Where The Under Comes From
The Fenway total is the one play tonight that is not about a team, it is about two pitchers at once. Payton Tolle carries the best ERA and the best WHIP on the whole card, 3.09 and 1.09, with 141 strikeouts in 125.1 innings. George Kirby is not in that class but he walks only 34 in 147.2 innings, so the traffic he gives up is earned rather than gifted.
The counterweight, and it should be said: Kirby's opponent batting average is .282, the highest of the seven starters who have a real season behind them. He gets hit. The bet is that Boston's bats have to string those hits together rather than being handed bases, and that Tolle keeps the other half of the scoreboard quiet.
Putting It Together
Four plays, seven units to win, 10.59 units at risk. Every one of them is a pitching opinion wearing a different market's clothing.
Rangers -1 at -165, 3 units. deGrom's command against the worst run prevention on the card. The Athletics have allowed 787 runs in 137 games.
Astros ML at -128, 1.5 units. Lambert's .222 opponent average against Kay's 2.30 strikeout to walk ratio. The thinnest edge of the four.
Red Sox and Mariners Under 8 at -120, 1 unit. Tolle's 1.09 WHIP against a Seattle offense with a .679 OPS.
Rays ML at -168, 1.5 units. A bullpen game in Tampa against a club that is 46-23 at home.
If you take one habit away from this page, make it this one: read WHIP and strikeout to walk before you read ERA. ERA tells you what already happened to a pitcher. The other two tell you what he keeps doing.