The Cubs slow start at home this season has resulted in 1-5 record; a winning percentage of .167; and a pace to lose 135 games this season.
Dempster has thrown two quality starts and has an 0-1 record and 1.88 ERA.
Quality pitching will keep a team in the game. But in order to win, the Cubs need to score.
And that is where our concept of "relative ERA" comes into play.
Normal ERA is taking the number of earned runs allowed divided by innings pitched and compared to a 9 inning game. For a starting pitcher, a generous "quality start" is loosely defined as 1 ER in 5 IP, 2 ER in 6 IP or 3 ER in 7 IP (range 1.80 to 3.86 ERAs) The average is 2.89.
But one must factor in whether the bullpen can hold a quality start to victory. The Cubs bullpen has been woeful so far. In six games this season, the pitching staff has given up 28 runs for a staff ERA of 4.67.
The Cubs offense has only mustered 19 runs in 6 games or 3.17 runs per game.
The difference between runs allowed and runs scored is 1.5 per game.
The run differential means that the pitching needs to be significant better in order to coax out a victory.
The relative staff ERA needs to come down below the Cubs run production of 3.17 runs per game.
And a "quality start" relative to the Cubs current offensive production needs to average a 1.39 ERA. So Dempster's stellar 1.88 ERA is not enough to generate one win. It is just not enough.
The starting pitchers have started to shoulder the "blame" for not completing what they started (the game) in these close losses, where either the offense failed to rally or the bullpen imploded. That puts more pressure on the starters to go beyond the norm in order to find success.
So relatively speaking, the Cub starters are under pressure to give up only 1 run per game. Then the bullpen is under pressure to give up only 1 run per game to total 2, since the Cubs offense is mired in only scoring 3 runs per contest.
