Not all baseball stadiums are created equal. The dimensions of the outfield, quantity of foul ground, heights of boundary walls and inclusion or absence of batter's eyes in the outfield play parts in the physical makeup of a ballpark. Likewise, altitude and humidity can have drastic effects on statistics for hitters and pitchers alike.

So, next time you're looking at a prospect's stats, consider the context in which they were accumulated. Especially at the extremes, ballpark context can make a massive difference in how a player's stats reflect actual performance.

Here's a look at the average number of runs per game for 21 leagues between 2008 and 2012.

But just as there are quirky dimensions and thin-air ballparks across pro ball, the way runs have been scored is also different. Statistically, there were 4.3 runs scored per game in the National League and Rookie-level Gulf Coast League. But while you're likely to see more extra-base hits at a Major League game, a greater percentage of those same 4.3 runs in the GCL have come via walks and errors.

To complement the bar chart above, here's a look at the run environment of those 21 leagues over the same five-year span.

A greater percentage of hits went for home runs at the highest level, as evidenced by the fact that over the past five years the American and National Leagues have ranked first and tied for second respectively in home run percentage.

Perhaps unsurprisingly, pitcher command has been worse at a younger age and a lower level. Four of the five leagues with the worst non-intentional walk rate were Class A Short-Season or Rookie-level leagues. Similarly, fielding percentage correlated directly with level.

Looking at specific Minor League classifications, there were differences between levels and often significant ones within levels.

At Triple-A, the PCL has been much more of a hitters' league than the International League. This was fueled by a higher batting averages as well as greater walk and home run rates. Stadiums such as the hitter-friendly Isotopes Park (Albuquerque), Aces Ballpark (Reno) and Security Service Field (Colorado Springs) were big contributors to those numbers.

By contrast, the three Double-A leagues were among the most balanced of any classification. Separated by just 0.2 runs per game, the Eastern, Southern and Texas Leagues sported similar batting averages, on-base percentages and slugging percentages.

At the other end of the spectrum, Class A Advanced remained one of the most unbalanced levels in professional baseball as the California League continued to live up to its reputation as a hitters' haven. Stats across the board (batting average, OBP, OPS, walks and home run rate) were higher than in the Carolina League -- generally a neutral environment -- and the Florida State League -- a notorious pitchers league which boasted the fewest runs/game and the only full-season league with a five-year OPS below .700.

Further down the chain stand the two evenly balanced, mostly neutral Class A leagues and a pair of short-season leagues which featured more walks, more errors and fewer homers.

At the lowest level -- Rookie ball -- were extreme hitters environments (Pioneer and Arizona Leagues) and stingy pitchers leagues (Gulf Coast and Dominican Summer Leagues). The GCL and DSL featured the two lowest five-year batting averages and home run rates as well as the two highest walk rates and fielding percentages.

Here's an in-depth look at the park factors for each of the full-season stadiums since 2010. Where a club has relocated or changed leagues, two parks between the three years were listed. The table looked at three counting stats -- runs, home runs and hits -- and used a formula to help compare one park from another.

((Runs scored at home + runs allowed at home)/(Home games)) / ((Runs scored on the road + runs allowed on the road)/(Road games))

Note: A park factor of 1.000 is considered neutral and represented an equal number of runs/homers/hits at home as on the road. A factor over 1.000 favors hitters, while a factor under 1.000 favors pitchers.

Triple-A

If the PCL is one of the most hitter-friendly leagues in the Minors, then Isotopes Park and Aces Ballpark must be the poster candidates for high-scoring, big-hitting, Triple-A launching pads. Security Service Field, at 6,531 feet above sea level, may have ranked first in the past, but a humidor installed in 2012 has limited the offense slightly.

But just how advantageous were these parks -- and the league as a whole -- for hitters?

Reno's Adam Eaton won the 2012 PCL batting title with a .381 average, teammate Ryan Wheeler finished second with a .351 mark, and five of the top 10 hitters -- including Albuquerque's Scott Van Slyke, who finished 10th with a .327 average -- played for the Isotopes or the Aces. In the IL, Gwinnett's Jose Constanza won the batting title with a .314 average, and only six hitters finished with an average north of .300.

In the PCL, strikeout leader John Ely of the Isotopes had the lowest ERA (3.20), and only seven qualifying pitchers posted a sub-4.00 mark. Back in the IL, Lehigh Valley's Tyler Cloyd went 12-1 with a league-best 2.35 ERA, and the top 21 pitchers by ERA all had marks below 4.00.

Columbus' Huntington Park -- which saw a total of 179 homers in 2012, a Triple-A best and second only to High Desert in the Minors -- can be considered the lone extreme hitters park in the International League.

Perspectives:
Toledo's Daniel Dorn batted .252 with 14 homers and 49 RBIs in 116 IL games in 2012. With 50 walks and 41 extra-base hits, Dorn posted a .344 on-base percentage, .777 OPS and tied for a team-best 170 total bases. His offensive numbers were around 2012 league averages, but it's worth noting that Fifth Third Field has regularly been one of the most pitcher-friendly parks in one of the most pitcher-friendly leagues.

Spare a thought for Dorn, drafted by the Reds in 2006 before being signed by the Tigers as a Minor League free agent last summer. Before playing in Toledo, he spent three-and-a-half years in the Bats infield. Louisville Slugger Field has been another notoriously difficult park for hitters.

Perspectives:
Considering there were a total of 594 homers at Isotopes Park over the past three years, Ely's 2012 campaign was better than the numbers suggest. He went 14-7 with 36 walks in 168 2/3 innings. His substantial ERA drop with Albuquerque (from 6.22 in 2010 and 5.99 in 2011) can be attributed to a career-low opponents' batting average (.238) and career-high strikeouts (165), something vital when you pitch in a park where even the most routine fly ball has a chance of leaving the yard. Ely's 2012 home ERA of 2.76 was actually better than his 3.72 road mark

Double-A

Double-A parks have played fairly consistent across the board over the past few years. Sure, Erie's Jerry Uht Park inflated hitting stats and Arkansas' Dickey-Stephens Park was a place where deep fly balls went to die, but there aren't the same extremes that you'll find in the PCL or Cal League.

Among the parks that played big was Birmingham's Regions Park. At 340 feet down the lines, 385 in the power alleys and 405 to center, the dimensions are not that unusual. But the Barons (and their opponents) hit a combined 162 homers at Regions Park between 2010-12, compared with 330 in the same number of games on the road. The club will open the brand-new Regions Field in April.

Perspectives:
Andy Wilkins led the Barons with 17 homers in 2012, but only three were hit at home. His 69 RBIs also were a team high, despite 51 coming on the road. He hit .201 with a .314 slugging percentage in 57 home games, but .273 with a .524 SLG in 59 games away from Birmingham.

Perspectives:
Southern League hurlers were among the most affected by the introduction of the Pensacola Blue Wahoos in 2012. Five County Stadium -- the home of the Carolina Mudcats, who moved to the Carolina League last year -- was historically a pitchers park. By contrast, Pensacola's Bayfront Stadium proved to favor home run hitters in its inaugural season with a league-high 120 longballs.

For example, J.C. Sulbaran surrendered 10 homers in 137 hitter-friendly Cal League innings in 2011. In 19 starts and 104 2/3 innings with Pensacola in 12, he allowed 17 en route to a league-worst 24 between the Blue Wahoos and Northwest Arkansas Naturals.

Class A Advanced

Nowhere in the Minors was there a bigger difference between leagues within the same classification. The Cal League boasted the greatest number of runs per game of any full-season league; the Florida State League ranked dead last, more than a full run behind.

High Desert's Stater Bros. Stadium topped the list for the most hitter-friendly home ballpark. When you consider the number of runs and homers at home, compared with the road, the Mavs' yard ranked No. 1 in pro ball. It also stood second (behind Isotopes Park for total hits).

Located in the middle of the desert in Adelanto, Calif., Stater Bros. Stadium has seen 604 homers in three years, 65 percent more than the 367 hit on the road in the same three-year span.

Perspectives:
Considering his home ballpark as well as the nature of the Florida State League, Brewers third baseman Mike Walker put together an impressive season in 2012. He hit .280 with 12 homers, tied for the team lead, and 75 RBIs, a Manatees high. His 54 walks led to a .361 on-base percentage and his final slugging percentage of .415 ranked first among regulars.

Deceptively, his average ranked 118th among all Class A Advanced hitters, while his 12 homers tied for 128th. But against the league averages -- .255 average, .326 OBP and .373 slugging percentage -- it's easy to see Walker's real value in a tough hitters environment. Expect a jump in production if he sees time in Huntsville in 2013.

Class A

Two average leagues in terms of run production, the Midwest and South Atlantic Leagues have been notable for extremes and exceptions.

In the Sally League for example, the difference between hitter-friendly McCormick Field (Asheville) and pitcher-friendly Grayson Stadium (Savannah) was 1,137 hits, 1,096 runs and 398 homers in just three years.

One quirk of the classification was that though Greensboro's NewBridge Bank Park favored batters in terms of hits and homers, it actually produced a below-average number of runs. Another was that Lansing's Cooley Law School Stadium produced an above-average number of hits and runs, but a below-average number of homers. The odd dimensions -- 412 feet to center, 305 down the lines -- have been attributed to squeezing the stadium in between two parallel city streets.

Perspectives:
Tip your cap to Asheville's Tyler Anderson -- the Rockies' No. 6 prospect. He led the Tourists to a Sally-best 88-52 record while ranking first with a 2.47 ERA and third with 12 wins. The secret to his success? A league-best .232 opponents average against and 2.09 walks per nine innings produced a stingy 1.08 WHIP, which ranked second only to Augusta's Clayton Blackburn. Away from the bandbox of McCormick Field, Anderson went 7-2 with a 1.83 ERA.