good luck to you on your continued improvement. i hope you dont go thru what i did when i was raised to a 5. i lost my next 10 matches in a row before i was brought back to a 4. i dont know about your situation but im the most experienced player on my team so im the one selected to play the best on the opposing team . im always playing a s/l 6 or higher and win 56.8% of the time. when i was a 5 i just couldnt get the extra points i needed to beat the higher level players. in the 10 matches i lost i scored enough points to win had i been a 4. guess you could say im a very strong 4 but a week 5. i had one of those real good nights last week beating an 8 pretty bad .i got 17 to his 3. guess i will be moving back up to a 5 after that. i know he wasnt sandbagging because he is my teamate in another division. i just had one of those nights where i couldt miss leaving him sitting in his chair when he wasnt racking lol.
I'm in the same boat, went up to SL5 last summer, and then went 3-10. I wasn't getting killed, just not closing the deal. I changed teams, and after a while my captain started putting me up against SL4s, and I started winning again. (We have enough higher level players that we can do that). Our team is tied for first, so I'm in no hurry to try the higher SLs any time soon. (The current strategy is working quite well!) But next session I need to work that out and take my turn at the SL5's and SL6's again.