When we compare bowling we look at average, Strike rate (SR) and Ecomomy Rate (ER), and tend to compare them. But the game has changed so much, the Ecomomy rates have risen. The following trends were studied in ODI bowlers stats. The qualification was 3000 balls bowled.
Averages and ERs are on the rise and SRs are coming down. But the SR lowering is not much compared to changes in averages and ERs.
What does this mean? ER of 4.0 in 2005 is better than Er of 4.0 in 1985, Avg of 27 today is better than that of 27 in 1985, and SR of 40 in 1985 better than a SR of 40 today. This may due to true betterment of some aspects of game. And equally it may not be.