Maron is like teflon. He somehow keeps getting selected, despite posting the lowest average by a Test batsman since 2013.
After the Test match against Zimbabwe in March 2013, Marlon's average stood at 37.54 (the highest since his fourth Test match against South Africa). Since then, he has averaged a woeful 25.02 in 48 innings.
Below is Marlon's career moving average. He has all but dropped off a cliff over the last 3 years.
*click to enlarge image
Looking at his career numbers, we see that his overall career average of 32.64 is largely due to the 16 Tests between between March 2011-March 2013 in which he averaged 55.54. In his first 29 Tests, he averaged 28.73, and has averaged 25.02 in the 26 Tests since that 16 game purple patch.
If you were to remove those 16 Tests (of which 5 came against Bangladesh and Zimbabwe), his average is 26.92. His median average score is 17. 12% of his 127 innings have resulted in a duck and 62.4% have yielded a score under 30.