i think, as others have written, that the phrase is "slick stick, lew stick." lew is possibly a play on words - a replacement for the word "glue" in its intended meaning. if stick is referring to a bat (which most agree on), the context for slick and glue makes sense and reinforces the idea of an inside joke/play on words, with glue having the opposite effect of a slick bat. "lew" and "glue" are a play on words as part of the inside joke, with the misspelling of lew unclear as to whether it was unintended are not. basically the translation of the inside joke is "slick stick, glue stick" possibly making light of criger's inability with the bat as a friendly rib as others have alluded to.
couple other things that might reinforce the idea it's an inside joke. one other comical reference in the piece is "cheer leader." it looks like tesreau might have been the one to write "cheer leader." maybe he was in a comical mood, or was a jokester in general. i couldn't find many autographed pieces from tesreau but here's an example with an loa from psa:
http://www.ebay.com/itm/Jeff-Tesreau...-/371331540269
the composition of the "h" in the link above and in the "cheer leader" reference seems similar and has some uniqueness to it in its form. the composition of the "r" in the "yours" part of "sincerely yours" is more well formed and looks much more like the two "r's" in "cheer leader" than the "r" in "tesreau." might just mean that tesreau had different compositions for a "r" whether he was taking time to write a word out versus scribbling his last name quickly. an autograph expert could probably poke holes at this, but...
finally, i found that the nickname "jeff" is itself a joke. it was given to him by sportswriters in reference to the "half-pint" character "jeff" in the "mutt and jeff" comic strip series. tesreau was a big, imposing spitball (maybe the spitball was part of the inside joke) pitcher at 6'2'' tall. tesreau could apparently take a joke as he took on the nickname of jeff. here's a link to this reference on pp. 104-105:
https://books.google.com/books?id=Rt...signed&f=false
alright, i've written enough quotations for many months and admit that there are a lot of suppositions in what i wrote but it's my best guess.