I strongly suspect all the ex grammar school people complaining about lack of grammar in the young don't know what an adverbial clause is either. What they may be right to complain about is young people finishing education unable to write sentences e.g. capital letters, full stops, spellings. This should be handled by new rules that young people stay in education or training until 18 and those with a low level of English and maths have to keep doing these until this age. Thus all the new grammar can be removed from year 6 SATS.
Are SATS in year 6 worth doing? Some children (particularly in London) do a whole range of tests for private schools and 11plus tests at age 11 which suggests that SATS are rather mild in comparison. I think if SATS are kept there should be one common test for 11plus, private selective schools so that children don't have to be so stressed and the tests might identify bright children whose parents are not pushy or interested or it hadn't occurred to them that their child could be bright. These children could be then set higher in comprehensive schools. However 10 or 11 year olds might have a bad day so they should not be used to set in stone. The main other problem is that they make year 6 a very boring year where little learning is done - they are often just taught to the test. I'm sure I learnt better without them. The problem with teacher assessments are that your child might not get on with the teacher or the teacher might be blinded by a pushy middle class family whenthe child is actually not very clever. The other issue is they just test english and maths when a child might be stronger in other areas. I think it might be better to replace SATS with a portfolio: here is my best story I have written in primary school (which would illustrate good use of grammar (or not)), here is my best piece of art work, a maths test, time taken in a running sprint (best of 3 attempts on different days), my responsibilities in year 6 are...
Tests at the beginning of school to measure progress sound like an excellent idea but in practice they don't work because little children are put under pressure when the emphasis should be settling them in to start learning. Perhaps they should be filled in by the preschool but should not be about academic learning - instead this child can hold a pencil, this child can concentrate for five minutes, this child can take turns. Children who do really badly could perhaps be held back