In this case, all of the characters were not even 平声 at all in Middle Chinese, but were all 入声 instead [Wiktionary's IPA]:
夹 (夾) /kˠɛp̚/
击 (擊) /kek̚/
All of the above started with voiceless unaspirated (obstruent) consonants, so are all 阴入 in Middle Chinese. For Standard Mandarin, these reflexes are notoriously ...