outfield, such as the "Short Porch in Right" at Yankee Stadium) which allow short home runs. There is an equivalent for this in cricket, where the placement of the pitch may render one perpendicular boundary significantly shorter than the other. For example, in a particular game, the leg-side boundary may be 15 feet closer to the batsman than the off-side boundary. Such a boundary can then be targeted by batmen in search of quick runs. The baseball behaves differently in those stadiums with artificial turf as well. Artificial surfaces are harder and more uniform than grass, and the ball tends to roll farther and straighter, and to bounce truer and more highly on these fields. Teams built to play the majority of their games on this field tend to place a higher premium on defence (since it is more likely to get an infield out) and speed (since it is more important to be able to beat out a throw) than on power hitting. The altitude of the stadium (most notably Coors Field) can also impact the distance a batted ball travels and the amount of ball movement a pitcher can generate with his deliveries, although recently balls have begun being placed in humidors at high-altitude parks to negate these effects. The amount of moisture in the dirt on the basepaths can also affect the behaviour of ground balls and the ease with which players may steal bases; some teams are known to alter the amount of watering done to the dirt depending on the skills of the home and visiting team. The amount of foul territory is also an important variable, since foul pop-ups that would be outs in some parks (e.g., the Oakland Coliseum) may end up in the stands in other parks, thereby allowing the batter to remain at the plate (e.g., Fenway Park and Coors Field). On the whole, though, these variations do not produce effects as great as variations in cricket pitches, with one arguable exception being Coors Field. In general, the condition of the pitch is a much greater factor in cricket than in baseball, while at the professional level stadium shape and quirks permanently built into the playing surface are greater factors in baseball than in cricket. Note that in amateur cricket pitches may have considerable variation in shape and may even incorporate obstacles (like tree roots), but this is not considered desirable